Step-by-step explanation:
The work-energy theorem states that the change in the kinetic energy is equal to the amount of work done.
Energy is ability to do work. To perform work, energy has to be spent.
Work is said to be done whenever the force is applied to an object then the object is moved to a certain distance.
When the displacement and the force applied are in an opposite direction then the work done is negative. for example, when a break is applied by a moving car.
When the displacement and the force applied are in same direction then the work done is positive. For example, the car is moving.