State the importance of work energy theorem .

Explanation

(1) If the change in kinetic energy `DeltaK ` of a body is zero , then the work done on the body is zero and its kinetic energy remains constant and hence the speed of the body remains constant .
For example : the speed of a particle in uniform circular motion is constant and work done is zero .
(2) If the displacement of a body is in the same direction of force or dispalce ment is in direction of component of force then the work done on the body and hence the kinetic energy of body increases .
For example ,free fall body .
(3) If the dispalcement of a body is opposite in the direction of force or displacement is in the opposite direction of component of force then the work done by the body and hence , the kinetic energy of body decreases .