Question

A ramp is often used to raise an object. if 90 joules of energy are needed to lift an object to a platform but 100 joules are used in rolling the object up the ramp, what percent energy was wasted in the form of heat due to friction

Answer 1

100 Joules have been used to roll the object up the ramp, but only 90 Joules were actually needed to lift the object, this means that 10 Joules have been wasted in the form of heat due to the friction between the object and the ramp, and this corresponds to
$\frac{10 J}{100 J} \cdot 100 = 10 \%$
so, 10 % of the energy.