Chapter 8, Problem 3A

Distinguish between force and impulse.

To determine

To explain: The difference between force and impulse.

Explanation of Solution

Introduction:

The concept of force and impulse are both related to the change in momentum of a moving body. A force can cause a change in momentum of a body and hence an acceleration as well. But the parameter of time which implies the duration for which a force is applied on the body completes the concept of momentum and this new parameter which requires considering force and time together is the impulse.

A force is something which when acts on a body of mass m produces acceleration. Here, the duration of force is not considered. The general expression for force is given by,

  $F=ma$

In most of the conditions, the time of motion of the body will be large and hence the parameters force and time are defined separately and effect of time does not play much of a role.

In some cases, a very large force or impact acts upon a body for a very short duration, the effect of the force along with time need to be considered as a whole and this product gives the parameter impulse.

When a force F is applied on a body for a particular duration t , then it produces an impulse, expressed as,

  $\text{Impulse}=Ft$

Now, considering the effect of force on the momentum , this implies that, the same force applied on a body for shorter and longer duration causes the momentum of the body to change differently.

This gives the clear difference between the concept of force and impulse on a moving body.