All practice questions

Question 341Question →

Identify the fluid dynamics at work by pairing each mechanical component or structural design with its correct convection mechanism.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The chimney relies on natural convection of gases; the ceiling fan uses forced convection of gases; the solar water heater uses natural convection of liquids; and the centrifugal pump uses forced convection of liquids.

Convection transfers heat through the macroscopic movement of fluids (gases or liquids). This movement can be natural, where heated fluid becomes less dense and rises, or forced, where a mechanical device moves the fluid. The correct pairs perfectly map each mechanical system to its specific fluid state and its specific driving force.

Step-by-Step Solution

1

Analyze each component to determine if it handles a gas (air or smoke) or a liquid (water or coolant).

The chimney and ceiling fan handle gases. The solar heater and centrifugal pump handle liquids.

Identifying the fluid medium narrows down the possible matches.

2

Determine if the fluid movement is driven by natural density differences (buoyancy) or by a mechanical device (pump or fan).

The chimney and solar heater are passive (natural convection). The ceiling fan and centrifugal pump are motorized (forced convection).

Distinguishing between natural and forced convection isolates the exact operational principle for each component.

3

Pair the components with the corresponding descriptions based on the fluid type and driving mechanism.

Chimney (natural gas) pairs with an upward draft. Ceiling fan (forced gas) pairs with disrupting stratification. Solar heater (natural liquid) pairs with passive liquid circulation. Pump (forced liquid) pairs with circulating liquid coolant.

Each description uniquely matches the state of matter and convection type of one specific component.

Key Concept

Convection occurs in both gases and liquids and can be driven naturally by density differences (buoyancy) or forced mechanically by fans and pumps.

Question 342Question →

Match each closed hydraulic system scenario to its calculated unknown value. Assume the fluid is incompressible, there is no friction, and conditions are ideal.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches are based on applying Pascal's Principle and the conservation of work. Output Force is 250 lbs, Output Area is 15 in², Input Force is 50 lbs, and Output Distance is 1 in.

Each matching pair applies either Pascal's Principle (

P = \frac{F_1}{A_1} = \frac{F_2}{A_2}

) or the conservation of work (

F_1 \cdot d_1 = F_2 \cdot d_2

) to solve for the missing variable in the hydraulic system.

Step-by-Step Solution

1

Calculate the Output Force for the first scenario.

250 lbs

Using Pascal's Principle (

F_1/A_1 = F_2/A_2

), the system pressure is 50 lbs / 2 in² = 25 psi. The output force is 25 psi * 10 in² = 250 lbs.

2

Calculate the Output Area for the second scenario.

15 in²

The system pressure is 30 lbs / 3 in² = 10 psi. Rearranging the formula for area (

A = F/P

), the output area is 150 lbs / 10 psi = 15 in².

3

Calculate the Input Force for the third scenario.

50 lbs

System pressure is determined by the output side: 100 lbs / 20 in² = 5 psi. The required input force is 5 psi * 10 in² = 50 lbs.

4

Calculate the Output Distance for the fourth scenario.

1 in

By conservation of work (

F_1 \times d_1 = F_2 \times d_2

), the input work is 40 lbs * 5 in = 200 in-lbs. Thus, the output distance is 200 in-lbs / 200 lbs = 1 in.

Key Concept

Pascal's Principle states that pressure applied to an enclosed fluid is transmitted undiminished. The work done on the input piston equals the work done by the output piston.

Question 343Question →

A primary driving gear with 20 teeth operates at a speed of $120\text{ rpm}$ . Match each potential driven gear, identified by its tooth count, to the resulting output speed it would produce when directly meshed with this driving gear.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The 10-tooth gear matches to

240\text{ rpm}

, the 20-tooth gear matches to

120\text{ rpm}

, the 40-tooth gear matches to

60\text{ rpm}

, and the 60-tooth gear matches to

40\text{ rpm}

.

The correct matches are derived using the fundamental gear ratio principle: the speed of a driven gear is inversely proportional to its number of teeth compared to the driving gear.

Step-by-Step Solution

1

Calculate the constant proportional value of the driving gear by multiplying its teeth by its speed.

20 \text{ teeth} \times 120\text{ rpm} = 2400

In a meshed gear system, the product of a gear's tooth count and its rotational speed remains constant for all meshing gears (

T_1 \times S_1 = T_2 \times S_2

).

2

Determine the output speed for each driven gear by dividing the constant value by its respective tooth count.

2400 \div 10 = 240

;

2400 \div 20 = 120

;

2400 \div 40 = 60

;

2400 \div 60 = 40

.

This isolates the unknown speed variable (

S_2

) for each specific gear configuration.

Key Concept

Gear Ratios and Speed Inverse Proportionality

Question 344Question →

Review the following gear train configurations. Match each specific gear arrangement to its resulting mechanical outcome or primary functional advantage.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Match the small driving gear to torque multiplication, the large driving gear to speed multiplication, the idler setup to identical direction/speed, and the worm gear to extreme reduction/self-locking.

Each arrangement fundamentally alters mechanical power in a distinct way: small-to-large increases torque, large-to-small increases speed, idlers are strictly for directional matching, and worm gears provide self-locking high-reduction.

Step-by-Step Solution

1

Analyze the 15-tooth driving to 60-tooth driven gear arrangement.

It operates as a step-down gear system with a 1:4 ratio.

A smaller driving gear turning a larger driven gear inherently increases torque at the expense of rotational speed.

2

Analyze the 60-tooth driving to 15-tooth driven gear arrangement.

It operates as a step-up gear system with a 4:1 ratio.

A larger driving gear turning a smaller driven gear increases output rotational speed but reduces the available torque.

3

Analyze the two 30-tooth gears connected by an idler.

The output gear spins at the exact same speed as the input gear, and in the same rotational direction.

The intermediate idler gear reverses the rotational direction twice, ensuring input and output spin identically. The idler's size has no mathematical effect on the overall 1:1 ratio between the identical 30-tooth gears.

4

Analyze the worm and spur gear setup.

It drastically drops speed and cannot be easily back-driven.

A worm drive behaves like a continuous screw; a single full rotation of the worm may only advance the spur gear by one tooth, yielding massive reduction. Additionally, the angle typically prevents the spur gear from turning the worm.

Key Concept

Mechanical Advantage and Function of Gear Trains

Question 345Question →

Match each wheel and axle mechanism to its corresponding force-distance trade-off profile and Ideal Mechanical Advantage (IMA).

Click a left item, then click its matching right item

Show answer & explanation

Answer

Screwdriver maps to IMA 6 (force multiplier). Bicycle maps to IMA 1/9 (distance multiplier). Steering wheel maps to IMA 14 (force multiplier). Ceiling fan maps to IMA 1/100 (speed multiplier).

Each mechanism is correctly paired by identifying where the effort is applied (wheel or axle) and calculating the ratio of the effort diameter to the load diameter. This ratio directly dictates whether the machine sacrifices distance for force (IMA > 1) or sacrifices force for distance/speed (IMA < 1).

Step-by-Step Solution

1

Identify the effort and load components for each mechanism.

Determine which part acts as the 'wheel' (larger radius) and which acts as the 'axle' (smaller radius), and definitively locate where the input effort is applied.

The formula for Ideal Mechanical Advantage requires knowing whether the input is applied to the wheel or the axle.

2

Calculate the Ideal Mechanical Advantage (IMA) for each item.

Using the formula IMA = (Diameter of Effort) / (Diameter of Load). Screwdriver: 1.5/0.25 = 6. Bicycle: 3/27 = 1/9. Steering Wheel: 14/1 = 14. Ceiling Fan: 0.5/50 = 1/100.

This mathematical ratio represents the mechanical trade-off of the machine.

3

Classify each mechanism based on its IMA value.

IMA > 1 (Screwdriver, Steering Wheel) means the machine multiplies force. IMA < 1 (Bicycle, Ceiling Fan) means the machine multiplies distance or speed.

A machine cannot multiply both force and distance simultaneously due to the conservation of energy.

Key Concept

Ideal Mechanical Advantage (IMA) of a Wheel and Axle

Question 346Question →

Match each specialized fastener or component to the primary mechanical function it serves in an assembly.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Shoulder Bolt matches with providing a bearing surface; Belleville Washer matches with compensating for thermal expansion; Castellated Nut matches with physically blocking rotation; Blind Rivet matches with expanding against an inaccessible panel.

Each fastener has a specific design intended for a unique mechanical application. Shoulder bolts provide bearing surfaces, Belleville washers maintain tension through spring action, castellated nuts provide positive locking via a pin, and blind rivets allow for one-sided installation.

Step-by-Step Solution

1

Analyze the function of a Shoulder Bolt.

Identified that it has an unthreaded 'shoulder' section.

This unthreaded section acts as a dowel or pivot point for linkages, pulleys, or sliding components.

2

Analyze the function of a Belleville Washer.

Identified that it is a conical spring washer.

Its conical shape allows it to act as a heavy spring, absorbing vibrations and thermal expansion to maintain bolt tension.

3

Analyze the function of a Castellated Nut.

Identified that it has slots cut into one end.

These slots are designed to receive a cotter pin that passes through the bolt, creating a positive lock against rotation.

4

Analyze the function of a Blind Rivet.

Identified that it is used when only one side of the workpiece is accessible.

A tool pulls a mandrel that deforms the blind end, clamping the materials together before the mandrel breaks off.

Key Concept

Specialized Fasteners and Locking Mechanisms

Question 347Question →

Based on Newton's First Law (Inertia), match each physical scenario on the left with the correct description of its resulting motion or force balance on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The elevator scenario pairs with passengers continuing downward; the turning vehicle pairs with objects moving in a straight path (appearing to move right); the stationary block pairs with remaining stationary due to no unbalanced forces; and the skydiver pairs with balanced forces resulting in zero net force.

Each pairing correctly applies the principle of inertia to a specific physical system. Newton's First Law explains both why moving objects resist stopping or turning (the elevator and vehicle scenarios) and why objects maintain their current state when forces are balanced (the stationary block and the constant-velocity skydiver).

Step-by-Step Solution

1

Analyze the descending elevator scenario.

Matches with passengers feeling pushed downward.

Newton's First Law states objects in motion stay in motion. The elevator stops, but the passengers' inertia carries them downward momentarily.

2

Analyze the vehicle turning left.

Matches with unsecured objects sliding to the right.

Objects tend to travel in a straight line. As the car turns left underneath them, their straight-line inertia makes them move right relative to the car.

3

Analyze the stationary block on a frictionless table.

Matches with remaining completely stationary.

An object at rest stays at rest unless acted upon by an external force, regardless of the lack of friction.

4

Analyze the skydiver at terminal velocity.

Matches with downward gravity balanced by upward air resistance.

Terminal velocity is a constant speed. A constant speed in a straight line means acceleration is zero, requiring a net force of zero.

Key Concept

Newton's First Law dictates that an object's state of motion (either at rest or moving at a constant velocity) will not change unless an unbalanced external force acts upon it. This resistance to change is known as inertia.

Question 348Question →

An engineering team is analyzing how different mechanical interactions affect the control and efficiency of an off-road vehicle. Match each vehicle component or scenario to the specific type of frictional resistance it primarily demonstrates.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches are: stationary tires demonstrate Static Friction; brake pads demonstrate Kinetic Friction; ball bearings demonstrate Rolling Friction; and moving through mud demonstrates Fluid Friction.

Each mechanical scenario perfectly isolates one of the four primary types of friction. Stationary objects resisting motion rely on static friction. Surfaces sliding past one another generate kinetic friction. Round objects moving over a surface experience rolling friction. Objects moving through a liquid or gas encounter fluid friction.

Step-by-Step Solution

1

Analyze the tire scenario

The tires are stationary relative to the rock surface.

Identifying that there is no relative motion points to static friction.

2

Analyze the brake pad scenario

The pads rub directly against the moving steel rotors.

Solid surfaces sliding against each other exhibit kinetic (sliding) friction.

3

Analyze the ball bearing scenario

The bearings roll along their inner and outer races.

Objects rolling over a surface experience rolling friction, which is much lower than sliding friction.

4

Analyze the mud scenario

The vehicle body pushes through a semi-liquid medium.

Moving through liquids or gases involves fluid (viscous) friction.

Key Concept

Types of Frictional Resistance in Mechanics

Question 349Question →

In the context of Newton's Third Law of Motion, every action force has a specific, equal, and opposite reaction force acting on a different body. Match each described action force on the left with its exact corresponding reaction force on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct pairings strictly follow the A-on-B / B-on-A rule, where the reaction force is always the exact same type of force exerted in the opposite direction by the receiving object back onto the originating object.

According to Newton's Third Law, forces always come in pairs. If body A exerts a force on body B, then body B simultaneously exerts an equal and opposite force on body A. The correct matches precisely swap the 'exerter' and the 'receiver' of the force while maintaining the identical fundamental type of force (gravitational, magnetic, aerodynamic, or mechanical).

Step-by-Step Solution

1

Analyze the action force to identify the two interacting bodies (Object A and Object B).

For example, in the skydiver scenario, Object A is the Earth and Object B is the skydiver.

Newton's Third Law strictly dictates that action and reaction forces must occur between two interacting objects.

2

Identify the type and direction of the force exerted by Object A on Object B.

The Earth exerts a downward gravitational force on the skydiver.

You must know the exact nature of the action force to find its true paired reaction.

3

Reverse the roles of the objects and the direction of the force to find the reaction.

The reaction must be Object B (the skydiver) exerting an upward gravitational force on Object A (the Earth).

Reaction forces are always equal in magnitude, opposite in direction, of the same type, and act on the opposing body.

4

Repeat this reversal process for all given scenarios and select the matching right-side items.

Helicopter on air pairs with air on helicopter; Magnet on steel pairs with steel on magnet; Nozzle on water pairs with water on nozzle.

This guarantees an accurate mapping of all Newton's Third Law pairs without falling for common distractors like balancing forces.

Key Concept

Newton's Third Law (Action/Reaction Pairs)

Question 350Question →

Match each mechanical scenario to its corresponding missing value (net force, mass, or acceleration) using Newton's Second Law ( $F = ma$ ).

Click a left item, then click its matching right item

Show answer & explanation

Answer

Match the scenarios by calculating the missing variable:

10 \text{ kg}

at

3 \text{ m/s}^2

matches

30 \text{ N}

;

100 \text{ N}

at

5 \text{ m/s}^2

matches

20 \text{ kg}

;

25 \text{ kg}

at

50 \text{ N}

matches

2 \text{ m/s}^2

;

200 \text{ kg}

at

4 \text{ m/s}^2

matches

800 \text{ N}

.

The correct matches are found by identifying the two known variables in Newton's Second Law (

F = ma

) for each scenario and algebraically solving for the third unknown variable.

Step-by-Step Solution

1

Calculate the net force for the gear assembly.

F = 10 \text{ kg} \times 3 \text{ m/s}^2 = 30 \text{ N}

Applying the direct formula

F = ma

to find the required force.

2

Calculate the mass of the mechanism.

m = \frac{100 \text{ N}}{5 \text{ m/s}^2} = 20 \text{ kg}

Rearranging the formula to

m = \frac{F}{a}

to solve for mass.

3

Calculate the acceleration of the engine block.

a = \frac{50 \text{ N}}{25 \text{ kg}} = 2 \text{ m/s}^2

Rearranging the formula to

a = \frac{F}{m}

to solve for acceleration.

4

Calculate the net force for the payload.

F = 200 \text{ kg} \times 4 \text{ m/s}^2 = 800 \text{ N}

Applying the direct formula

F = ma

to find the required force.

Key Concept

Newton's Second Law (

F = ma

)

Question 351Question →

In a mechanical system where a solid weight is swung in a horizontal circle on a tether, match each observed physical action or effect with the correct physics terminology.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct pairings match the inward pull to centripetal force, the release direction to tangential path, the resistance to turning to inertia, and the outward sensation to the centrifugal effect.

In circular motion, the tether provides an inward centripetal force. Inertia is the mass's resistance to turning, causing the centrifugal effect (outward sensation). If the tether breaks, this inertia carries the mass in a straight tangential path.

Step-by-Step Solution

1

Analyze the inward pulling force described in the first scenario.

Matches with 'Centripetal force'.

By definition, the net inward force keeping an object in circular motion is the centripetal force.

2

Determine the path of the object if the tether breaks.

Matches with 'Tangential path'.

Newton's First Law states an object will move in a straight line if no net force acts upon it, making its path tangent to the circle.

3

Identify the property causing resistance to turning.

Matches with 'Inertia'.

Inertia is the fundamental resistance of mass to any change in its state of motion.

4

Identify the term for the apparent outward push.

Matches with 'Centrifugal effect'.

The sensation of being thrown outward is a perceived effect in a rotating frame, known as the centrifugal effect.

Key Concept

Circular Motion and Centripetal Force

Question 352Question →

Structural engineers select specific cross-sectional profiles based on how they distribute internal stresses under different physical loads. Match each structural shape to its defining mechanical behavior.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct pairings are: I-Beam matches with maximum vertical bending resistance; Hollow Circular Tube matches with uniform torsional resistance; C-Channel matches with flat mounting surface combined with bending resistance; and Angle Iron matches with bidirectional corner stiffness.

Each cross-section is geometrically optimized for distinct force applications: I-beams isolate material at the extremes to fight bending, circular tubes use symmetry to fight torsion, C-channels offer mounting utility, and angle irons provide simple two-axis corner support.

Step-by-Step Solution

1

Analyze the I-Beam profile and its typical load.

Matched to vertical bending resistance.

The horizontal flanges of an I-beam are placed far from the neutral axis to absorb the maximum tension and compression forces of a bending moment.

2

Evaluate the geometric properties of a Hollow Circular Tube.

Matched to uniform torsional resistance.

Because it has a continuous, symmetrical closed shape, it resists twisting forces equally well regardless of the rotational direction.

3

Identify the functional advantage of a C-Channel.

Matched to the combination of a flat mounting surface and bending resistance.

The flat back (web) allows it to be mounted flush against walls or vehicle chassis, while the protruding flanges provide structural strength.

4

Assess the role of an Angle Iron.

Matched to bidirectional stiffness for corners.

The L-shape reinforces joints by preventing flex in both the vertical and horizontal planes simultaneously.

Key Concept

Cross-sectional geometry dictates a structural member's ability to handle specific types of stress (bending, torsion, shear).

Estimated Time:1m 30s

Question 353Question →

Match each mechanical procedure involving a change in temperature to the physical result it produces.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Heating the nut causes expansion that increases its inner diameter; chilling the bearing causes contraction that reduces its outer diameter; heating the closed cylinder causes fluid expansion that increases internal pressure.

Each mechanical action correctly pairs with its fundamental thermal behavior: adding heat causes expansion (increasing size or pressure), while removing heat causes contraction (decreasing size).

Step-by-Step Solution

1

Analyze the effect of heating the stuck nut.

The nut expands, increasing its inner diameter.

Added thermal energy increases molecular spacing, causing the entire solid object (including any holes within it) to expand outward.

2

Analyze the effect of chilling the steel bearing.

The bearing contracts, decreasing its outer diameter.

Removing thermal energy decreases molecular spacing, shrinking the overall size of the metal part.

3

Analyze the effect of heating trapped fluid.

The fluid attempts to expand, creating high pressure.

Liquids expand when heated, and being confined in a closed space turns this volumetric expansion into severe internal pressure.

Key Concept

Thermal expansion causes materials to increase in size when heated, while thermal contraction causes them to decrease in size when cooled. This principle affects solids and liquids across various mechanical systems.

Question 354Question →

Match each mechanical system or scenario with the correct description of its convective heat transfer process.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Engine coolant matches forced convection into a liquid; the radiator blower matches forced convection into a gas; the smokestack matches natural convection of a heated gas; and the reversed ceiling fan matches forced convection overcoming gas buoyancy.

Each mechanical application relies on a specific interaction between a solid and a fluid, or manipulates fluid flow using either mechanical force or natural buoyancy. The pump moves a liquid medium, the blower moves a gaseous medium across solid fins, the smokestack utilizes density differences, and the ceiling fan directly opposes thermal rising.

Step-by-Step Solution

1

Determine if each scenario relies on a mechanical device (forced convection) or fluid density differences (natural convection).

The pumped coolant, the radiator blower, and the ceiling fan are forced convection. The unpowered smokestack is natural convection.

Categorizing the primary driving force narrows down the available matching options.

2

Identify the fluid medium and the direction of fluid movement for the forced convection scenarios.

Coolant is a liquid absorbing heat from a solid. Radiator air is a gas absorbing heat from a solid. The ceiling fan actively pushes warm air down against its natural tendency to rise.

Matching the specific fluid states (liquid vs. gas) and unique flow paths firmly links each remaining scenario to its correct definition.

Key Concept

Convection is 'forced' when a mechanical device (pump, fan) moves the fluid, and 'natural' when temperature-induced density changes cause the fluid to rise or fall.

Question 355Question →

Match each gear arrangement with its resulting mechanical effect on speed, torque, or rotational direction.

Click a left item, then click its matching right item

Show answer & explanation

Answer

A small driver to a large driven gear decreases speed and increases torque. A large driver to a small driven gear increases speed and decreases torque. Two directly meshed gears rotate in opposite directions. An idler gear between two gears allows the input and output to rotate in the same direction.

Each physical gear arrangement corresponds to a single, consistent mechanical law: size differences alter the speed/torque ratio inversely, while the number of meshing points dictates rotational direction.

Step-by-Step Solution

1

Analyze the size relationship for the first two scenarios.

A smaller driver turning a larger gear trades speed for torque (gear reduction). A larger driver turning a smaller gear trades torque for speed (overdrive).

Understanding the fundamental trade-off between speed and torque is required to match size differences with output changes.

2

Analyze the rotational direction for direct mesh versus an idler train.

Direct mesh always reverses direction. Adding a single idler gear reverses it again, making the output match the input direction.

Counting the number of gears in a train determines the final direction of rotation.

Key Concept

Basic Gear Ratios and Rotational Direction

Estimated Time:1m 0s

Question 356Question →

Match each hydraulic jack scenario to its correctly calculated parameter based on Pascal's Principle.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Jack A matches to 160 lbs output force, Jack B matches to 3 inches output distance, Jack C matches to 4 in² input area, and Jack D matches to 30 psi fluid pressure.

Each hydraulic system operates on Pascal's Principle and the conservation of volume. By applying the formulas for pressure (

P = F/A

) and mechanical advantage (

MA = A_{out}/A_{in}

), the missing parameter for each jack can be calculated and uniquely matched.

Step-by-Step Solution

1

Calculate the output force for Jack A.

F_{out} = 160 \text{ lbs}

.

Using Pascal's principle, mechanical advantage is

12/3 = 4

.

F_{out} = 40 \times 4

.

2

Calculate the output distance for Jack B.

d_{out} = 3 \text{ inches}

.

Due to volume conservation,

d_{in} \times A_{in} = d_{out} \times A_{out}

.

15 \times 2 = d_{out} \times 10

.

3

Calculate the input area for Jack C.

A_{in} = 4 \text{ in}^2

.

Since pressure is equal across the system,

P = 180 / 24 = 7.5 \text{ psi}

.

A_{in} = 30 / 7.5

.

4

Calculate the fluid pressure for Jack D.

P = 30 \text{ psi}

.

Pressure equals force over area,

P = 45 / 1.5

.

Key Concept

Pascal's Principle, Fluid Volume Conservation, and Mechanical Advantage

Question 357Question →

Match each standard component of a basic refrigeration cycle to its primary function.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Compressor maps to pressurizing gas, Condenser maps to releasing heat outside, Expansion Valve maps to dropping pressure, and Evaporator maps to absorbing heat from inside.

In a standard vapor-compression refrigeration cycle, the compressor increases pressure, the condenser rejects heat outdoors, the expansion valve lowers pressure, and the evaporator absorbs heat indoors.

Step-by-Step Solution

1

Identify the power source and prime mover of the cycle.

The Compressor is matched with pressurizing and pumping the refrigerant gas.

It provides the mechanical work necessary to drive the refrigerant through the loop.

2

Identify where the system gets rid of collected heat.

The Condenser is matched with releasing heat to the outside air.

Condensation requires heat to be expelled from the hot vapor into the cooler outdoor surroundings.

3

Identify the component that prepares the refrigerant to absorb heat.

The Expansion Valve is matched with dropping the pressure of the liquid refrigerant.

A sudden drop in pressure causes a drop in temperature, making the fluid cold enough to absorb indoor heat.

4

Identify where the system actually cools the intended space.

The Evaporator is matched with absorbing heat from the inside air.

As warm indoor air blows over the cold coils, the liquid refrigerant absorbs the heat and evaporates into a gas.

Key Concept

Refrigeration Cycle Components and Functions

Question 358Question →

Match each physical property of a fluid to its correct definition.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Density matches 'The mass of a fluid per unit of its volume.' Specific Gravity matches 'The ratio of a fluid's density compared to the density of pure water.' Viscosity matches 'A fluid's internal resistance to flowing.' Compressibility matches 'The measure of a fluid's volume decrease when placed under pressure.'

Each fluid property has a distinct operational definition in mechanical systems: density is mass over volume, specific gravity compares that density to water, viscosity measures flow resistance, and compressibility measures volume change under pressure.

Step-by-Step Solution

1

Identify the definition of density.

Density is mapped to mass per unit volume.

This is a fundamental physical property of all matter that determines its weight for a given size.

2

Identify the definition of specific gravity.

Specific gravity is mapped to the ratio of a fluid's density to water.

It acts as a unitless multiplier comparing a fluid to a standard baseline.

3

Identify the definition of viscosity.

Viscosity is mapped to internal resistance to flow.

It dictates how easily fluids move through mechanical components like pipes and engines.

4

Identify the definition of compressibility.

Compressibility is mapped to how much volume decreases under pressure.

This property separates liquids (nearly incompressible) from gases (highly compressible) in hydraulic and pneumatic systems.

Key Concept

Foundational fluid properties determine how fluids behave and function in mechanical, hydraulic, and pneumatic applications.

Estimated Time:45s

Question 359Question →

Match each mechanical adjustment to its primary physical effect on frictional resistance.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Motor oil decreases the coefficient of friction; adding cargo increases the normal force; ball bearings replace sliding friction with rolling friction; and changing the resting face of a crate leaves the frictional resistance unchanged.

Each adjustment demonstrates a fundamental principle of friction. Oil modifies the surface interaction (lowering the coefficient of friction). Added mass increases the normal force (increasing total resistance). Bearings change the physical mechanism from sliding to rolling. Finally, rotating the crate tests the principle that friction is independent of the contact area.

Step-by-Step Solution

1

Analyze the effect of motor oil.

It creates a fluid boundary layer.

Lubrication physically separates the sliding metal surfaces, which directly reduces the coefficient of friction.

2

Analyze the effect of heavier cargo.

The downward force on the floor increases.

Friction is proportional to normal force. More weight means a greater normal force, increasing total frictional resistance.

3

Analyze the effect of ball bearings.

Sliding motion is converted to rolling motion.

Rolling friction relies on point or line contact and avoids the continuous shearing of surface asperities seen in sliding friction.

4

Analyze the effect of changing the crate's contact area.

The frictional force does not change.

According to Coulomb's laws of friction, kinetic friction is independent of the apparent area of contact as long as the mass (and thus normal force) remains constant.

Key Concept

Friction and Resistance

Question 360Question →

Match each described action force with its corresponding reaction force according to Newton's Third Law of Motion.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Each action force must be paired with a reaction force that is equal in magnitude, opposite in direction, and acting on the original body.

Newton's Third Law states that for every action, there is an equal and opposite reaction. To correctly identify the corresponding pair, you simply reverse the 'pusher' and the 'receiver' objects, and reverse the physical direction of the force.

Step-by-Step Solution

1

Identify the two interacting objects in each scenario.

The paired objects are identified (e.g., swimmer/water, hammer/nail, rocket/gas, box/floor).

Reaction forces always occur between the exact same two interacting bodies.

2

Determine the direction of the action force.

The initial force directions are identified (e.g., backward, downward).

The reaction force must be in the exact opposite direction.

3

Select the reaction force that swaps the acting object and reverses the direction.

The correct matches are successfully established.

This satisfies the fundamental definition of action and reaction pairs.

Key Concept

Newton's Third Law (Action/Reaction)

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept