Question

Your uncle pushes a $60.0kg$ crate along a floor with average speed $v=0.65m/s$ for $5.0$ seconds as he moves furniture to clean up the garage.
If the coefficient of friction between the floor and the crate is $\mu =0.340$, what is the average power output of your uncle during this time?

• A. $26.0W$
• B. $130W$
• C. $383W$
• D. $650W$
• E. None of the above

Answer 1

The correct option is B $130W$

Given : $\mu =0.340$ $v=0.65$ m/s $m=60.0$ kg

As the crate moves with constant speed, thus the force applied by uncles must be equal to the frictional force.

$\therefore$ $F=\mu mg=0.340\times 60.0\times 9.8=199.92$ N

Average power output $P=Fv=199.92\times 0.65\approx 130$ W