Question

The total work done on a particle is equal to the change in its kinetic energy.

This statement is true for which of the condition?

• A. always
• B. only if the forces acting on the body are conservative
• C. only if the forces acting on the body are gravitational
• D. only if the forces acting on the body are elastic.

Answer 1

The correct option is A always

From Newton's second law, it can be shown that work on a free, rigid body, is equal to the change in kinetic energy of the velocity and rotation of that body,

$W=\Delta KE$

The work of forces generated by a potential function is known as potential energy and the forces are said to be conservative. Therefore work on an object that is merely displaced in a conservative force field, without change in velocity or rotation, is equal to minus the change of potential energy of the object,

$W=-\Delta PE$

These formulas demonstrate that work is the energy associated with the action of a force, hence the total work done on a particle is equal to the change in its kinetic energy always.