Answer to Question #148239 in Classical Mechanics for Isurini Sirisena

Question

In loading a delivery van, the driver pushed a 15 kg crate for
5 metres up a ramp. He had to push with a force of 132 N and
the vertical height gained was 1.3 m. What was the efficiency of
pushing this crate up the ramp onto the back of the van?

Answer 1

Answer

Length of ramp

$=\sqrt{5^2+1.3^2}=5.17m$

Net work done is equal to change in potential energy

$W=U=mgh$

$=15\times10\times1.3$

$W=195J$

Total work done

$W=Fd=132\times1.57$

$W=682.44J$

Efficiency is given by

$\eta=\frac{195}{682.44}\times100=29.12\%$