Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time.The power expended in raising the 50-kg sack is
A)twice as much.
B)half as much.
C)the same.
D)impossible to predict without further information

Question

Quizplus · Accepted Answer

Power is defined as work done per unit time. Since both sacks are lifted in the same time, the work done on each sack is equal to its weight multiplied by the distance it is lifted.

For the 50-kg sack, the work done is:

W = Fd = mgd = (50 kg)(9.8 m/s^2)(2 m) = 980 J

For the 25-kg sack, the work done is:

W = Fd = mgd = (25 kg)(9.8 m/s^2)(4 m) = 980 J

Therefore, the work done on each sack is the same. Since the time taken to lift each sack is the same, the power expended in raising each sack must also be the same.

Therefore, the answer is C, the same.

Both a 50-Kg Sack Is Lifted 2 Meters from the Ground