Answer to Question #206861 in Physics for Mohamed Wael

Question

Prove that work net is positive when an object is speeding up. (Use the Work-Kinetic Energy theorem)

Answer 1

The net work done on a particle equals the change in the particle’s kinetic energy:

$$W=K_B-K_A$$

According to this theorem, when an object slows down, its final kinetic energy is less than its initial kinetic energy, the change in its kinetic energy is negative, and so is the net work done on it. If an object speeds up, the net work done on it is positive.