List of practice Questions

A body of mass 2 kg initially at rest moves under the action of an applied horizontal force of 7 N on a table with coefficient of kinetic friction = 0.1. Compute the 

1. work done by the applied force in 10 s, 
2. work done by friction in 10 s, 
3. work done by the net force on the body in 10 s, 
4. change in kinetic energy of the body in 10 s, and interpret your results.

A body of mass 0.5 kg travels in a straight line with velocity v =a x \(^{3/2}\) where a = 5 m\(^{-1/2}\) s–1 . What is the work done by the net force during its displacement from x = 0 to x = 2 m ?

A person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the mass is dissipated.
(a) How much work does she do against the gravitational force ?
(b) Fat supplies 3.8 × 10\(^7\)J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?