Question

State and explain work energy principle.

Answer 1

Hint: Basically the net work done on any object is the change in the kinetic energy of that object and energy is known as the capacity for doing that work.

Complete step-by-step answer:

Work is done on an object when we transfer some energy to that object, suppose if one object transfers energy to the second object it means that the first object has done work on the second object or we can say that it's the measure of energy transfer which occurs when an object is moved over a distance by an external force applied in the direction of the displacement.

Energy is the capacity to do work which exists in potential, kinetic, thermal, nuclear, electrical, chemical and various other forms.

Now the work-energy principle states that an increase in the amount of kinetic energy of a rigid body is caused by the equal amount of positive work done on the body by the resultant force acting on that body and on the contrary, the decrease in the amount of kinetic energy is caused by an equal amount of negative work done by the resultant force.

For example a ball is dropped from a certain height so the velocity of the ball is increasing gradually due to gravitational acceleration which results in increase in its kinetic energy hence work done is positive and suppose a car applies break and comes into rest after few seconds therefore the speed of the car decreases hence kinetic energy also decreases therefore the work done by the break is negative.

Note: The rate of doing work is equal to the rate of using energy since the force transfers one unit of energy so as to do one unit of work this means that whenever a force is applied to an object and causing the object to move work is done by the force and the unit of work is same as the unit of energy i.e. joule.