A person lifts a box of mass 10 kg to a height of 2 m in 4 seconds. What is the

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Question: A person lifts a box of mass 10 kg to a height of 2 m in 4 seconds. What is the power exerted by the person?

Options:

Correct Answer: 50 W

Solution:

The work done against gravity is W = mgh = 10 kg * 9.8 m/s² * 2 m = 196 J. Power is P = W/t = 196 J / 4 s = 49 W, approximately 50 W.

A person lifts a box of mass 10 kg to a height of 2 m in 4 seconds. What is the power exerted by the person?

A person lifts a box of mass 10 kg to a height of 2 m in 4 seconds. What is the power exerted by the person?

Step 1: Identify the mass of the box, which is 10 kg.
Step 2: Identify the height the box is lifted to, which is 2 m.
Step 3: Use the formula for gravitational force, which is approximately 9.8 m/s².
Step 4: Calculate the work done (W) using the formula W = mgh, where m is mass, g is gravitational force, and h is height.
Step 5: Substitute the values into the formula: W = 10 kg * 9.8 m/s² * 2 m.
Step 6: Calculate the work done: W = 10 * 9.8 * 2 = 196 J (joules).
Step 7: Identify the time taken to lift the box, which is 4 seconds.
Step 8: Use the formula for power (P), which is P = W/t, where W is work done and t is time.
Step 9: Substitute the values into the power formula: P = 196 J / 4 s.
Step 10: Calculate the power: P = 49 W (watts).
Step 11: Round the power to approximately 50 W if needed.

Work and Energy – Understanding the calculation of work done against gravitational force using the formula W = mgh.
Power – Calculating power as the rate of doing work, using the formula P = W/t.
Units of Measurement – Recognizing and converting units of work (Joules) and power (Watts).