Question

A weight-lifter lifts a weight of $2000N$ straight up to a height of $2.25m$ in $0.65$ seconds. The weight-lifter kept holding the weight at the same height for the next $4$ seconds before dropping it to the floor.
Find out how much power did the weight lifter use to lift the weights overhead?

• A. $2925watts$
• B. $3077watts$
• C. $4500watts$
• D. $6923watts$
• E. $9100watts$

Answer 1

The correct option is D $6923watts$

We know that work done , $W=Fd\cos \theta$

Given $F=2000N,d=2.25m,t=0.65s$ and $\theta =0$ (because force and displacement are in the same direction)

$W=2000\times 2.25\times \cos 0=4500J$

Now , power $P=W/t=4500/0.65=6923W$