Tüm alıştırma soruları

5215 soru

Tüm türler5,215 Çoktan seçmeli2,665 Çoklu seçim6 Doğru / Yanlış260 Sayısal512 Eşleştirme930 Sıralama396 Boşluk doldurma397 Kısa cevap49

Soru 2201Soru →

In an automotive anti-lock braking system (ABS), specialized electrical and hydraulic components work together to prevent wheel lockup during hard braking. Match each ABS component to its primary operating function.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Cevabı ve açıklamayı göster

Cevap

Wheel speed sensor matches monitoring rotational speed and transmitting frequency signals; Tone ring matches rotating with the hub to induce voltage pulses; ABS electronic control unit matches processing wheel data to detect slip and command changes; Hydraulic control unit matches regulating fluid pressure via solenoids and a pump.

In modern anti-lock braking systems, each component performs a specialized task: the tone ring provides physical interruptions as it rotates with the wheel, the wheel speed sensor converts these into an electrical frequency signal, the ABS ECU interprets deceleration rates to determine if a wheel is locking, and the hydraulic control unit executes pressure hold, decay, and buildup cycles through internal solenoid valves and an electric pump.

Adım Adım Çözüm

Differentiate between the sensor and the reluctor target

The tone ring is the mechanical toothed target attached to the axle/hub, while the wheel speed sensor is the electromagnetic detector reading the pulses.

Understanding the physical interaction between the magnetic sensor and the toothed ring is essential for wheel speed detection.

Distinguish between electronic processing and hydraulic modulation

The ABS ECU executes electronic decision-making logic, whereas the HCU performs mechanical and hydraulic valve operations to modulate fluid pressure.

The ECU serves as the digital computer of the system, while the HCU serves as the hydraulic actuator.

Anahtar Kavram

Anti-lock Braking System (ABS) Component Roles and Hydraulic Modulation

Tahmini Süre:1m 0s

Soru 2202Soru →

An automotive technician is inspecting an engine lubrication circuit. Match each lubrication system component with its primary operational function.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

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Cevap

Anti-drainback valve matches preventing filter drainage during shutdown; Oil cooler matches dissipating excess thermal energy; Oil pressure regulating valve matches bleeding surplus pressurized oil at high speeds; Oil pickup screen matches straining coarse particles before the pump inlet.

Each lubrication system component performs a specific function: the anti-drainback valve prevents startup starvation by keeping oil in the filter, the oil cooler prevents viscosity loss by removing heat, the pressure regulating valve limits maximum circuit pressure at high RPM, and the pickup screen shields the pump from coarse sump debris.

Adım Adım Çözüm

Identify the purpose of the anti-drainback valve located inside the oil filter.

It retains oil inside the filter body when the engine is turned off.

Maintaining oil in the filter prevents dry start conditions and reduces bearing wear upon ignition.

Determine the operational role of an engine oil cooler.

It transfers excess heat from motor oil to the engine coolant or ambient air.

Regulating oil temperature prevents thermal breakdown and preserves the lubricating film strength under high loads.

Analyze the function of the oil pressure regulating (relief) valve.

It opens a bypass route back to the pan or pump inlet when pressure exceeds the calibrated spring force.

Because positive displacement pumps increase flow with engine RPM, the relief valve prevents burst filter gaskets and overpressurization.

Evaluate the role of the mesh screen on the oil pickup tube.

It traps large contaminants in the oil pan sump before fluid enters the pump.

Pre-filtering protects the tight-tolerance gears or rotors inside the oil pump from scoring and jamming.

Anahtar Kavram

Operational roles and protective functions of automotive engine lubrication system components

Tahmini Süre:1m 0s

Soru 2203Soru →

A circular fountain has a diameter of $12$ meters and is surrounded by a paved walkway that is $3$ meters wide. Which of the following represents the area of the walkway in square meters?

180\pi

81\pi

45\pi

6\pi

Cevabı ve açıklamayı göster

Cevap: $45\pi$

Cevap

The correct answer is

45\pi

The correct answer is found by subtracting the area of the inner circle from the area of the larger outer circle. The inner radius is

6

meters (half of the

12

-meter diameter), giving an area of

36\pi

. The outer radius is

9

meters (

6

meters plus the

3

-meter walkway), giving a total area of

81\pi

. The difference is

81\pi - 36\pi = 45\pi

Adım Adım Çözüm

Find the radius of the inner fountain.

12 \div 2 = 6

meters.

The area formula for a circle requires the radius, which is half of the diameter.

Calculate the area of the fountain.

Area =

\pi \times 6^2 = 36\pi

square meters.

This establishes the area of the space not covered by the walkway.

Find the radius of the total circular area (fountain plus walkway).

6 + 3 = 9

meters.

The walkway adds

3

meters to the radius of the inner circle.

Calculate the total area.

Area =

\pi \times 9^2 = 81\pi

square meters.

This gives the combined area of both the fountain and the walkway.

Subtract the fountain's area from the total area.

81\pi - 36\pi = 45\pi

square meters.

Subtracting the inner area isolates the area of just the paved walkway.

Anahtar Kavram

To find the area of a ring (annulus), calculate the area of the outer circle and subtract the area of the inner circle.

Soru 2204Soru →

During engine cranking, the starter pinion gear engages the flywheel ring gear to turn the crankshaft. Once the engine starts and begins running under its own power, which component protects the starter motor by preventing the engine flywheel from spinning the starter armature at destructive speeds?

Rectifier bridge assembly

Overrunning clutch

Solenoid pull-in winding

Alternator stator winding

Cevabı ve açıklamayı göster

Cevap: Overrunning clutch

Cevap

The overrunning clutch prevents the running engine from spinning the starter motor armature at excessive speeds.

The overrunning clutch (also known as a one-way clutch or starter drive clutch) allows torque to flow in only one direction: from the starter armature to the flywheel ring gear. The moment the internal combustion engine fires and begins spinning faster than the starter motor, the internal rollers or sprags release, allowing the pinion to spin freely (freewheel) until the solenoid disengages the pinion from the flywheel.

Adım Adım Çözüm

Identify the mechanical challenge present when an internal combustion engine starts.

The gear ratio between the starter pinion and the flywheel ring gear is roughly 15:1 to 20:1. When the engine starts and revs to 1,000 RPM, the starter motor would be forced to spin at 15,000 to 20,000 RPM if mechanically locked.

Such high rotational speed would cause centrifugal force to throw the starter armature windings and destroy the motor instantly.

Determine which starting system component provides one-way torque transfer.

The overrunning (one-way) clutch in the starter drive locks in one direction to crank the flywheel, but freewheels when the engine flywheel turns faster than the starter motor.

This mechanical decoupling disengages torque transfer from the engine back to the starter armature until the pinion fully retracts.

Anahtar Kavram

Starter motor drive protection and one-way overrunning clutch operation

Tahmini Süre:1m 0s

Soru 2205Soru →

Angle $A$ and Angle $B$ are supplementary angles. If the measure of Angle $A$ is $(6x - 10)^\circ$ and the measure of Angle $B$ is $(4x + 30)^\circ$ , what is the measure of Angle $A$ ?

106^\circ

32^\circ

86^\circ

122^\circ

Cevabı ve açıklamayı göster

Cevap: $86^\circ$

Cevap

The measure of Angle

A

86^\circ

The correct answer is

86^\circ

. Because Angle

A

and Angle

B

are supplementary, their measures add up to

180^\circ

. Setting up the equation

(6x - 10) + (4x + 30) = 180

and combining like terms yields

10x + 20 = 180

. Solving for

x

gives

x = 16

. Substituting

16

into the expression for Angle

A

(

6x - 10

) results in

6(16) - 10 = 86^\circ

Adım Adım Çözüm

Set up an equation based on the definition of supplementary angles.

(6x - 10) + (4x + 30) = 180

Supplementary angles always have a combined sum of

180^\circ

Combine like terms on the left side of the equation.

10x + 20 = 180

Grouping the

x

terms (

6x + 4x

) and constant terms (

-10 + 30

) simplifies the algebraic expression.

Isolate the variable term by subtracting

20

from both sides.

10x = 160

This removes the constant from the variable side, beginning the process of solving for

x

Divide by

10

to solve for

x

x = 16

Dividing both sides by the coefficient isolates

x

Substitute the value of

x

back into the expression for Angle

A

6(16) - 10 = 96 - 10 = 86^\circ

The question asks for the specific measure of Angle

A

, not just the value of the variable

x

Anahtar Kavram

Supplementary angles are two angles whose measures add up to

180^\circ

. To find unknown measures, set the sum of their algebraic expressions equal to

180

, solve for the variable, and substitute it back into the target expression.

Soru 2206Soru →

In an automotive drum brake assembly, which component receives hydraulic fluid pressure from the master cylinder to force the brake shoes outward against the rotating drum?

Brake caliper

Brake rotor

Wheel cylinder

Shock absorber

Cevabı ve açıklamayı göster

Cevap: Wheel cylinder

Cevap

The wheel cylinder is the hydraulic component in a drum brake assembly that expands outward to push the brake shoes against the drum.

In a drum brake system, hydraulic pressure generated by the master cylinder travels through brake lines into the wheel cylinder. The wheel cylinder contains dual opposing pistons that expand outward, pushing the brake shoes against the inner friction surface of the rotating brake drum to slow the wheel.

Adım Adım Çözüm

Identify the braking system type specified in the stem

The scenario specifically asks about a drum brake assembly and its internal hydraulic actuation.

Automotive braking systems are divided into disc and drum configurations, each utilizing distinct hydraulic actuators and friction components.

Distinguish between disc brake and drum brake components

Disc brakes use calipers and pads against a rotor, while drum brakes use wheel cylinders and shoes inside a drum.

Understanding component roles ensures correct identification of the actuator that converts hydraulic line pressure into mechanical force.

Select the component that converts hydraulic fluid pressure into outward mechanical force

The wheel cylinder houses pistons that push outward against the ends of the primary and secondary brake shoes.

Pressurized fluid from the master cylinder fills the wheel cylinder cavity, forcing its internal pistons and pushrods outward.

Anahtar Kavram

Drum Brake Hydraulic Actuation and Component Roles

Tahmini Süre:45s

Soru 2207Soru →

Why does an automotive lubrication system require a spring-loaded pressure relief valve when using a positive displacement oil pump?

To prevent oil circulation until the engine reaches its optimal operating temperature

To maintain hydraulic pressure exclusively during the intake and compression strokes of the engine

Because positive displacement pump output increases with engine speed, requiring excess pressure to be diverted to prevent system damage

To convert mechanical hydraulic pressure into electrical voltage for the engine charging system

Cevabı ve açıklamayı göster

Cevap: Because positive displacement pump output increases with engine speed, requiring excess pressure to be diverted to prevent system damage

Cevap

A spring-loaded pressure relief valve is required because a positive displacement pump produces increasing volume and pressure as engine RPM rises, necessitating a relief passage to bleed off dangerous excess pressure.

Positive displacement oil pumps deliver a fixed displacement of oil per revolution. Because the pump is driven directly or indirectly by the crankshaft or camshaft, higher engine RPM forces substantially more oil volume into fixed bearing clearances, creating high hydraulic pressure. The spring-loaded pressure relief valve opens when pressure reaches a predetermined threshold, safely venting excess oil back to the oil pan or pump inlet to prevent damage to the filter, gaskets, and pump drive.

Adım Adım Çözüm

Analyze the mechanical operating characteristic of a positive displacement engine oil pump.

A positive displacement pump moves a fixed volume of oil with every rotation, meaning total volume and resulting pressure increase directly with engine speed.

Understanding pump mechanics explains why oil pressure naturally rises as engine RPM climbs.

Determine the hydraulic consequence of unrestricted oil pump output at elevated engine speeds.

Without regulation, excessive oil pressure would rupture oil filters, blow out seals, and place unnecessary mechanical load on the pump drive.

Identifying potential failure modes clarifies the necessity of an active pressure limit.

Identify how the spring-loaded relief valve prevents excessive pressure buildup.

When hydraulic pressure exceeds the spring tension, the valve opens and diverts excess oil back to the oil pan or pump inlet.

Confirming the valve's bypass function matches the mechanical requirement of the system.

Anahtar Kavram

Positive Displacement Oil Pump Pressure Regulation

Tahmini Süre:1m 0s

Soru 2208Soru →

A rectangular landing pad is designed so that its length is exactly three times its width. If the total area of the landing pad is $147$ square meters, what is the perimeter of the landing pad in meters?

Cevabı ve açıklamayı göster

Cevap: 56

Cevap

By setting the width as

w

and length as

3w

, the area equation is

3w^2 = 147

. Solving for

w

yields a width of

7

meters, making the length

21

meters. The perimeter is the sum of all four sides:

2(21 + 7) = 56

meters.

Adım Adım Çözüm

Define variables and set up the area equation.

w \times 3w = 147

The area of a rectangle is width times length, and the length is given as three times the width.

Solve for the width (

w

w^2 = 49 \Rightarrow w = 7

Dividing both sides by

3

isolates

w^2

, and taking the square root gives the width.

Calculate the length and the perimeter.

Length =

21

, Perimeter =

56

Length is

3 \times 7

. Perimeter is

2(21 + 7)

Anahtar Kavram

Calculating the perimeter of a rectangle when given its area and the proportional relationship between its sides.

Soru 2209Soru →

A drone takes off from a launch pad and flies $8$ kilometers due north. It then turns and flies $15$ kilometers due east. What is the straight-line distance from the launch pad to the drone's current position?

13

kilometers

17

kilometers

23

kilometers

60

kilometers

Cevabı ve açıklamayı göster

Cevap: $17$ kilometers

Cevap

The straight-line distance is

17

kilometers.

The drone's path forms a right triangle because north and east are perpendicular directions. The straight-line distance between the launch pad and the current position is the hypotenuse. Using the Pythagorean theorem, we calculate

8^2 + 15^2 = 289

. The square root of

289

17

, making the straight-line distance

17

kilometers.

Adım Adım Çözüm

Identify the shape formed by the drone's flight path.

The path forms a right triangle, with the north and east paths as the legs.

North and east directions are perpendicular to each other, creating a

90^\circ

angle.

Set up the Pythagorean theorem equation.

a^2 + b^2 = c^2

, where

a = 8

and

b = 15

The straight-line distance from the start to the current position represents the hypotenuse (

c

Square the lengths of the two legs and add them together.

8^2 + 15^2 = 64 + 225 = 289

This calculates the value of

c^2

according to the theorem.

Find the square root of the sum to determine the hypotenuse.

\sqrt{289} = 17

Taking the square root of

c^2

gives the actual straight-line distance.

Anahtar Kavram

The Pythagorean theorem (

a^2 + b^2 = c^2

) is used to find the hypotenuse of a right triangle when both legs are known.

Soru 2210Soru →

A technician is preparing a replacement master cylinder for installation by performing a bench bleeding procedure to purge trapped air. What is the correct sequence of steps to properly complete this procedure?

Öğeleri doğru sıraya koymak için sürükleyin

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Cevap

The correct sequence begins by mounting the master cylinder level in a vise, followed by installing bleeder tubes routed into the reservoir, filling the reservoir so the tube ends are submerged in clean brake fluid, and finally slowly depressing the piston until all air bubbles cease escaping.

Bench bleeding is performed prior to vehicle installation to eliminate air trapped in the master cylinder bores. The cylinder must first be clamped level, followed by installing the bleed tubes, filling the reservoir to submerge the tube ends, and finally cycling the piston slowly until all air bubbles are expelled.

Adım Adım Çözüm

Clamp the master cylinder level in a bench vise.

The master cylinder is held securely and horizontal.

Prevents spillage and ensures both the primary and secondary chambers fill evenly.

Attach the bleeder adapters to the outlet ports and route the plastic hoses into the reservoir.

A closed fluid loop is created between the hydraulic ports and reservoir.

Allows fluid and air to exit the ports and recirculate into the reservoir without admitting outside air.

Fill the reservoir with new brake fluid above the hose discharge ends.

The outlet hose ends are completely submerged in brake fluid.

Ensures only brake fluid—not atmospheric air—is drawn into the cylinder bore on the piston release stroke.

Depress the master cylinder piston slowly using a blunt tool and allow it to return fully, repeating until bubbles stop.

Trapped air is completely expelled from the internal piston passages.

Evacuating air prior to installation prevents a soft, spongy brake pedal and reduces on-vehicle bleeding time.

Anahtar Kavram

Master Cylinder Bench Bleeding Procedure

Tahmini Süre:1m 0s

Soru 2211Soru →

When testing a vehicle with the engine running at 2,000 RPM, a digital multimeter connected across the battery terminals measures 17.6 volts, causing the battery casing to swell and the instrument cluster lamps to blow. What charging system component is failing to govern this electrical output?

Rectifier diode assembly

Voltage regulator

Starter solenoid switch

Ignition ballast resistor

Cevabı ve açıklamayı göster

Cevap: Voltage regulator

Cevap

Voltage regulator

The voltage regulator is designed to keep charging voltage within a safe, predetermined window (usually 13.5 to 14.8 volts). If the voltage regulator shorts or fails to restrict field current supplied to the spinning rotor, the alternator generates unregulated high voltage proportional to engine speed, leading to overcharging symptoms such as swollen battery cases and blown light bulbs.

Adım Adım Çözüm

Analyze the measured voltage against normal operational parameters.

A reading of 17.6 volts exceeds the standard automotive operating range of 13.5 to 14.8 volts, indicating a severe overcharging condition.

Vehicle charging systems must maintain a regulated DC voltage window to recharge the battery without boiling electrolyte or damaging sensitive electronics.

Identify the component responsible for limiting alternator output voltage.

The voltage regulator controls the amount of magnetic field current sent through the alternator rotor windings.

When the regulator fails closed or short-circuits, maximum field current is continuously supplied, allowing output voltage to climb excessively with engine RPM.

Anahtar Kavram

Alternator Voltage Regulation and Overcharging Diagnosis

Tahmini Süre:1m 0s

Soru 2212Soru →

A windshield wiper assembly has a total length of $20$ inches from its pivot point to its tip. The innermost $4$ inches of the assembly is a bare metal arm, and the outer $16$ inches is the rubber wiper blade. When turned on, the assembly sweeps back and forth through an angle of $135^\circ$ . What is the total area of the windshield that is wiped by the rubber blade during one sweep? (Leave your answer in terms of $\pi$ )

144\pi

sq in.

96\pi

sq in.

36\pi

sq in.

12\pi

sq in.

Cevabı ve açıklamayı göster

Cevap: $144\pi$ sq in.

Cevap

The correct answer is

144\pi

sq in.

The region wiped by the blade forms a shape called an annulus sector. To find its area, we calculate the area of the larger sector created by the full assembly (radius = 20) and subtract the area of the smaller un-wiped sector created by the metal arm (radius = 4). Both sectors cover a

135^\circ

angle, which is

\frac{3}{8}

of a full circle. Large sector area is

\frac{3}{8}\pi(20^2) = 150\pi

, and small sector area is

\frac{3}{8}\pi(4^2) = 6\pi

. The difference is

144\pi

Adım Adım Çözüm

Identify the geometric shapes involved in the problem.

The total area swept is a large circular sector with a radius of

20

inches. The inner un-wiped area is a smaller circular sector with a radius of

4

inches. The wiped area is the difference between them.

The rubber blade starts

4

inches away from the pivot, leaving a small sector un-wiped.

Determine the fraction of a full circle the wiper sweeps.

\frac{135^\circ}{360^\circ} = \frac{3}{8}

of a circle.

Sector area requires knowing what fraction of the total

360^\circ

circle is being used.

Calculate the area of the large sector (total sweep).

\text{Area} = \frac{3}{8} \times \pi \times (20)^2 = \frac{3}{8} \times 400\pi = 150\pi \text{ sq in.}

This finds the entire area enclosed by the 20-inch assembly.

Calculate the area of the small un-wiped sector.

\text{Area} = \frac{3}{8} \times \pi \times (4)^2 = \frac{3}{8} \times 16\pi = 6\pi \text{ sq in.}

This finds the area swept only by the bare metal arm.

Subtract the un-wiped area from the total area.

150\pi - 6\pi = 144\pi \text{ sq in.}

Subtracting gives the area exclusively wiped by the rubber blade.

Anahtar Kavram

Sector Area of an Annulus

Soru 2213Soru →

An automotive technician is performing a routine engine oil and filter replacement on a passenger vehicle. What is the correct sequence of steps to perform this service properly from beginning to end?

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence is: (1) Position a catch pan and remove the drain plug to drain the used oil, (2) Replace the oil filter while lubricating the new gasket, (3) Reinstall the drain plug and fill the engine with fresh oil, and (4) Run the engine briefly to prime the system and verify the final level with the dipstick.

A standard engine lubrication service must follow a logical sequence to protect engine components and prevent fluid loss. First, the contaminated oil is drained from the oil pan while warm. Second, the oil filter is replaced, making sure the new rubber gasket is lubricated with clean oil to prevent tearing upon installation. Third, the drain plug is reinstalled and torqued to specification before pouring in the specified amount of fresh motor oil. Finally, the engine is started to build oil pressure and prime the dry filter canister, after which the engine is shut off to allow oil to settle for an accurate final dipstick reading.

Adım Adım Çözüm

Evacuate the used engine oil.

Contaminated engine oil drains into the catch basin.

Old oil containing suspended soot, acid, and metal particles must be completely removed before servicing the rest of the circuit.

Install the replacement oil filter.

The old filter is removed and a new filter with a pre-lubricated rubber gasket is secured hand-tight.

Applying clean oil to the new filter gasket prevents friction bunching during tightening, ensuring a proper seal against the engine block.

Seal the sump and refill with clean oil.

The drain plug is torqued into place and new multi-grade motor oil is poured into the crankcase.

Closing the sump prevents fresh oil from escaping onto the shop floor when filling the engine.

Pressurize the system and verify fluid level.

Oil pressure is confirmed on the instrument cluster, the filter media is primed, and the dipstick confirms proper capacity.

The new filter holds a significant volume of oil; circulating fluid before the final dipstick check ensures the engine is not underfilled during operation.

Anahtar Kavram

Engine Oil and Filter Service Procedure

Tahmini Süre:1m 0s

Soru 2214Soru →

In the provided technical drawing, two horizontal parallel lines are intersected by a diagonal transversal line. The measures of two same-side interior angles are given by the expressions $(8x - 14)^\circ$ and $(6x + 26)^\circ$ . What is the numerical value of $x$ ?

Cevabı ve açıklamayı göster

Cevap: 12

Cevap

The two angles described are same-side interior angles. Because the lines are parallel, these angles are supplementary and their sum is exactly 180 degrees. Setting up the equation

(8x - 14) + (6x + 26) = 180

and solving for

x

correctly yields exactly 12.

Adım Adım Çözüm

Identify the relationship between the two given angles.

The angles are supplementary.

When two parallel lines are cut by a transversal, same-side interior angles are supplementary, meaning their sum is exactly 180 degrees.

Set up an algebraic equation.

(8x - 14) + (6x + 26) = 180

The sum of the measures of the two supplementary angles must equal 180.

Combine the like terms on the left side of the equation.

14x + 12 = 180

Adding the variable terms (

8x + 6x = 14x

) and the constant terms (

-14 + 26 = 12

) simplifies the equation.

Isolate the variable term.

14x = 168

Subtracting 12 from both sides of the equation leaves only the variable term on the left side.

Solve for x.

x = 12

Dividing both sides by 14 gives the final numerical value of x.

Anahtar Kavram

Same-side interior angles formed by parallel lines and a transversal are supplementary.

Soru 2215Soru →

A motor pool has a fleet of $40$ vehicles available for dispatch. The fleet consists of $25$ HMMWVs, $10$ transport trucks, and $5$ tactical ambulances. If a dispatcher selects one vehicle at random for a surprise inspection, what is the probability, expressed as a fraction in simplest form, that the selected vehicle is a tactical ambulance?

Cevabı ve açıklamayı göster

Cevap: 1/8; 1 / 8

Cevap

1/8

The probability of an event is found by dividing the number of favorable outcomes by the total number of possible outcomes. There are 5 tactical ambulances out of a total 40 vehicles. The resulting fraction is 5/40, which simplifies to 1/8 by dividing both the numerator and the denominator by 5.

Adım Adım Çözüm

Identify the total number of possible outcomes.

The total number of vehicles in the motor pool is

40

The denominator of a single event probability fraction represents the total number of items in the population.

Identify the number of favorable outcomes.

There are

5

tactical ambulances.

The numerator represents the count of the specific target items being selected.

Set up the probability ratio and simplify the fraction.

The initial ratio is

\frac{5}{40}

. Dividing both the numerator and denominator by

5

yields

\frac{1}{8}

Probability is the ratio of favorable outcomes to total outcomes, and the question requires the answer in simplest fraction form.

Anahtar Kavram

Single Event Probability

Soru 2216Soru →

A passenger train leaves West Station heading east toward East Station, which is $270$ miles away, traveling at a constant speed of $60$ mph. Exactly $1$ hour later, a freight train leaves East Station heading west toward West Station on a parallel track at a constant speed of $45$ mph. How many hours after the passenger train's departure will the two trains pass each other?

Cevabı ve açıklamayı göster

Cevap: 3

Cevap

3 hours

The passenger train travels 60 miles in its first hour, leaving 210 miles between the trains. Traveling toward each other, their combined relative speed is 105 mph. It takes them 2 hours to cover the 210 miles together. Adding the initial 1 hour, the total time since the passenger train departed is 3 hours.

Adım Adım Çözüm

Calculate the distance covered by the passenger train during its 1-hour head start.

60 \text{ mph} \times 1 \text{ hour} = 60 \text{ miles}

This establishes how much distance is covered before the second train begins moving.

Find the remaining distance between the two trains.

270 \text{ miles} - 60 \text{ miles} = 210 \text{ miles}

This is the remaining gap the two trains must close together once both are moving.

Calculate the combined (relative) speed of the two trains.

60 \text{ mph} + 45 \text{ mph} = 105 \text{ mph}

Because they are traveling toward each other from opposite directions, their speeds add up to close the distance.

Determine the time it takes to close the remaining 210 miles.

210 \text{ miles} \div 105 \text{ mph} = 2 \text{ hours}

Using the formula Time = Distance / Rate.

Calculate the total time since the passenger train's departure.

1 \text{ hour} + 2 \text{ hours} = 3 \text{ hours}

The question specifically asks for the time after the passenger train's departure, which includes its initial 1-hour head start.

Anahtar Kavram

Relative motion and converging objects with staggered start times

Soru 2217Soru →

In a vehicle equipped with front disc and rear drum brakes, which hydraulic valve limits fluid pressure to the rear wheels during heavy braking to prevent premature lockup?

Metering valve

Pressure differential valve

Proportioning valve

Residual pressure valve

Cevabı ve açıklamayı göster

Cevap: Proportioning valve

Cevap

Proportioning valve

The proportioning valve is engineered specifically to limit hydraulic line pressure delivered to the rear brakes under hard deceleration. As vehicle weight shifts forward onto the front suspension during heavy braking, the rear tires lose traction; the proportioning valve restricts rear line pressure to prevent rear-wheel lockup and directional skidding.

Adım Adım Çözüm

Identify the vehicle braking dynamic during heavy stops

Dynamic weight transfers forward toward the front axle, significantly reducing traction on the lighter rear axle.

Because less normal force acts on the rear tires during rapid deceleration, the rear wheels require less hydraulic clamping force to avoid lockup.

Evaluate the specific hydraulic valve designed to control rear brake pressure

The proportioning valve reduces the rate of hydraulic pressure increase to the rear drum brakes once a predetermined line pressure threshold is reached.

This pressure modulation prevents the rear wheels from locking prematurely, maintaining vehicle stability and steering control.

Anahtar Kavram

Hydraulic Brake Proportioning and Directional Stability

Tahmini Süre:1m 0s

Soru 2218Soru →

When an operator turns the ignition key to the START position, a specific electromechanical sequence occurs to crank the engine. What is the correct chronological sequence of these operational events from first to last?

Öğeleri doğru sıraya koymak için sürükleyin

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Cevap

The correct chronological sequence is: (1) Low-amperage current flows through the ignition switch and safety interlock to energize the starter solenoid coil, (2) The solenoid magnetic field draws the plunger inward, pivoting the shift fork to mesh the starter pinion gear with the flywheel ring gear, (3) The internal contact disc bridges the high-current battery terminal to the starter motor terminal, and (4) High-amperage current energizes the starter motor armature and field coils, spinning the crankshaft.

The automotive starting system follows a strict protective sequence. Turning the ignition key first sends low-amperage current through the safety switch to energize the solenoid electromagnet. As the solenoid plunger pulls inward, it physically pivots the shift lever to mesh the pinion gear with the flywheel ring gear before the motor spins. At full travel, the plunger forces a copper contact disc across the heavy battery terminals, allowing massive electrical current from the battery to flow into the starter motor windings, safely cranking the engine without grinding the gears.

Adım Adım Çözüm

Identify the initial electrical trigger in the starting circuit.

Turning the key closes the low-current control circuit through the safety switch to energize the starter solenoid winding.

The low-current control circuit must be energized first to trigger mechanical and high-current electrical operations safely.

Determine the mechanical engagement action resulting from solenoid magnetization.

The moving plunger pulls the shift lever, sliding the overrunning clutch and pinion gear into mesh with the engine flywheel ring gear.

Pinion gear engagement must occur prior to full motor rotation to prevent grinding and tooth damage.

Identify the high-current circuit switching point.

Near the end of plunger travel, a heavy copper contact disc bridges the main battery cable terminal and the starter motor feed terminal.

The solenoid acts as a high-current relay, only switching hundreds of amps once mechanical engagement is established.

Determine the final motor rotation phase.

High-current rushes into the starter motor brushes, field windings, and armature, rotating the pinion and cranking the engine.

With full battery power applied to the motor and the gears already meshed, rotational torque is transmitted to the crankshaft.

Anahtar Kavram

Electromechanical sequencing in automotive starting circuits

Tahmini Süre:1m 0s

Soru 2219Soru →

During a routine service inspection, an engine crankcase is significantly overfilled with motor oil well above the maximum mark on the dipstick. What operational issue will most likely occur if the engine is run under this condition?

The four-stroke cycle stalls during the compression stroke because excess oil enters the cylinder head and locks the exhaust valves open.

The engine coolant thermostat fails to open because excessive oil volume restricts the flow of coolant through the engine block.

The rotating crankshaft strikes the oil surface and whips it into foam, leading to oil pump cavitation and reduced oil pressure.

The combustion chamber develops a severely lean fuel mixture because surplus crankcase oil absorbs incoming vaporized gasoline.

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Cevap: The rotating crankshaft strikes the oil surface and whips it into foam, leading to oil pump cavitation and reduced oil pressure.

Cevap

The rotating crankshaft strikes the oil surface and whips it into foam, leading to oil pump cavitation and reduced oil pressure.

When an engine is overfilled with motor oil, the level in the oil pan reaches the path of the rotating crankshaft counterweights. At operating speeds, the spinning counterweights violently churn the liquid oil into a frothy foam. Because positive displacement oil pumps cannot pressurize aerated oil containing air pockets, the pump experiences cavitation, resulting in a dangerous drop in oil pressure and oil starvation to critical friction bearings.

Adım Adım Çözüm

Analyze the physical relationship between the oil pan reservoir and the rotating assembly when the oil level is excessive.

When the crankcase is overfilled, the oil level rises high enough to contact the spinning crankshaft counterweights and connecting rod journals.

The oil pan is designed to hold oil below the rotational path of the crankshaft under normal fill levels.

Determine the fluid dynamic effect of the high-speed crankshaft whipping through the oil reservoir.

The mechanical churning action aerates the motor oil, converting liquid lubricant into a frothy foam filled with air pockets.

Rapid agitation of liquid motor oil in the presence of crankcase air causes severe foaming.

Evaluate how foamed, aerated oil impacts the positive displacement oil pump and bearing lubrication.

The oil pump cannot pump compressible air bubbles efficiently, causing cavitation, a sudden drop in engine oil pressure, and accelerated bearing wear.

Engine oil pumps are designed to draw incompressible liquid; pumping aerated foam collapses hydraulic pressure in the oil galleries.

Anahtar Kavram

Crankcase Overfill and Oil Aeration/Cavitation

Tahmini Süre:1m 0s

Soru 2220Soru →

Automotive braking systems rely on specialized mechanical and hydraulic components to ensure balanced stopping power and driver control. Match each braking component on the left with its correct operational function on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

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Vacuum booster check valve pairs with maintaining negative pressure inside the power assist unit; Caliper slide pins pair with permitting floating housing movement to clamp both friction pads; Parking brake cable equalizer pairs with distributing mechanical tension evenly between rear wheel assemblies; Brake shoe return springs pair with pulling friction linings away from the friction surface when hydraulic pressure is released.

Each component fulfills a dedicated mechanical or hydraulic role: the vacuum booster check valve preserves vacuum assist reserve under varying engine loads; caliper slide pins enable single-piston floating calipers to center and apply dual-sided pad pressure; the cable equalizer balances mechanical pulling force across both rear wheels for the emergency/parking brake; and brake shoe return springs retract drum linings away from the drum when the brake pedal is released.

Adım Adım Çözüm

Identify the primary function of the vacuum booster check valve.

The check valve is a one-way valve installed at the booster inlet that retains engine vacuum in the power diaphragm chamber during low-vacuum conditions or engine shutdown.

Power assist relies on manifold vacuum differential; trapping negative pressure provides reserve power assist.

Identify the primary role of caliper slide pins in a floating disc brake setup.

Slide pins provide a lubricated track allowing the caliper assembly to slide horizontally, engaging the outer pad simultaneously with the inner pad.

Without slide pins, a single-piston caliper would only press the inner pad against the rotor.

Determine the mechanical purpose of the parking brake cable equalizer.

The equalizer pivots to balance pulling force equally across both left and right rear parking brake cables.

Equal tension ensures symmetrical mechanical holding force on both sides of the vehicle.

Determine the role of brake shoe return springs in drum brake hardware.

Heavy return springs pull the primary and secondary shoes back against the anchor pin when hydraulic fluid pressure drops.

Drum brakes lack natural disc wobble or seal rollback and require heavy mechanical springs to prevent continuous dragging.

Anahtar Kavram

Automotive braking system mechanical and auxiliary component functions

Tahmini Süre:1m 0s

ÖncekiSayfa 111 / 261Sonraki

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