Question

Difficulty: MediumWork, Energy, and Power

Four electric winches perform mechanical work by lifting loads vertically at constant speed. Arrange the lifting tasks in order of the mechanical power delivered, from least power to greatest power.

  1. 1Lifting a 500 N500\text{ N} load a distance of 3 m3\text{ m} in 30 s30\text{ s}
  2. 2Lifting a 200 N200\text{ N} load a distance of 5 m5\text{ m} in 10 s10\text{ s}
  3. 3Lifting a 400 N400\text{ N} load a distance of 2 m2\text{ m} in 4 s4\text{ s}
  4. 4Lifting a 150 N150\text{ N} load a distance of 4 m4\text{ m} in 2 s2\text{ s}

Answer

The correct sequence from least power to greatest power is: Lifting 500 N500\text{ N} by 3 m3\text{ m} in 30 s30\text{ s} (50 W50\text{ W}), Lifting 200 N200\text{ N} by 5 m5\text{ m} in 10 s10\text{ s} (100 W100\text{ W}), Lifting 400 N400\text{ N} by 2 m2\text{ m} in 4 s4\text{ s} (200 W200\text{ W}), and Lifting 150 N150\text{ N} by 4 m4\text{ m} in 2 s2\text{ s} (300 W300\text{ W}).
Power is the rate at which work is performed: P=F×dtP = \frac{F \times d}{t}. Evaluating each winch: the 500 N500\text{ N} load lifted 3 m3\text{ m} in 30 s30\text{ s} produces 50 W50\text{ W}; the 200 N200\text{ N} load lifted 5 m5\text{ m} in 10 s10\text{ s} produces 100 W100\text{ W}; the 400 N400\text{ N} load lifted 2 m2\text{ m} in 4 s4\text{ s} produces 200 W200\text{ W}; and the 150 N150\text{ N} load lifted 4 m4\text{ m} in 2 s2\text{ s} produces 300 W300\text{ W}. Arranged from lowest to highest wattage, the sequence is 50 W→100 W→200 W→300 W50\text{ W} \rightarrow 100\text{ W} \rightarrow 200\text{ W} \rightarrow 300\text{ W}.

Step-by-Step Solution

1
Recall the formula for mechanical power in terms of force, distance, and time.
Power is defined as work divided by time: P=Wt=F×dtP = \frac{W}{t} = \frac{F \times d}{t}, measured in watts (W\text{W}).
Power measures the rate at which work is accomplished rather than total energy expended.
2
Calculate the power output for each lifting task.
Task 1: 500 N×3 m30 s=1500 J30 s=50 W\frac{500\text{ N} \times 3\text{ m}}{30\text{ s}} = \frac{1500\text{ J}}{30\text{ s}} = 50\text{ W}. Task 2: 200 N×5 m10 s=1000 J10 s=100 W\frac{200\text{ N} \times 5\text{ m}}{10\text{ s}} = \frac{1000\text{ J}}{10\text{ s}} = 100\text{ W}. Task 3: 400 N×2 m4 s=800 J4 s=200 W\frac{400\text{ N} \times 2\text{ m}}{4\text{ s}} = \frac{800\text{ J}}{4\text{ s}} = 200\text{ W}. Task 4: 150 N×4 m2 s=600 J2 s=300 W\frac{150\text{ N} \times 4\text{ m}}{2\text{ s}} = \frac{600\text{ J}}{2\text{ s}} = 300\text{ W}.
Determines the exact numerical power rating for each winch.
3
Sort the values in ascending order from least to greatest.
50 W<100 W<200 W<300 W50\text{ W} < 100\text{ W} < 200\text{ W} < 300\text{ W}.
Satisfies the ordering criteria specified in the stem.

Key Concept

Mechanical power is the rate of doing work: P=Wt=F×dtP = \frac{W}{t} = \frac{F \times d}{t}.
Estimated Time:1m 30s
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