(a) State what is meant by positive work and negative work in the context of a body…
PHYSICS · Multi-part · AP · Physics C: Mechanics · Work Energy and Power · Work Energy and Power
Problem
(a) State what is meant by positive work and negative work in the context of a body whose speed is changing.
(a) State what is meant by positive work and negative work in the context of a body whose speed is changing.
(b) A truck of mass 4000kg is moving at 15m/s. The driver applies the brakes and the truck comes to rest in a short distance. Explain, without using any numerical calculation, whether the work done by the brakes on the truck is positive or negative.
(c) The magnitude of the work done by the brakes in part (b) is found to be equal to the change in the truck’s kinetic energy. Give a reason to justify why no additional information about the braking process (such as time taken or distance covered) is required to arrive at this equality.