# Newton's second law of motion

## Contents

## Statement

### In terms of force and acceleration

The net external force on a system is the product of the total mass of the system and the acceleration of its center of mass (here, mass is a scalar quantity and both force and acceleration are vector quantities). In symbols:

.

In particular, the direction of the net external force is the same as the direction of acceleration of the center of mass.

For a point mass or particle, we can talk of the acceleration of the whole body, and thus in the above refers to the acceleration of the point mass.

### In terms of momentum and impulse

The net external impulse exerted on a system over a time period equals the difference between the final and initial values of its linear momentum. In other words, if the impulse from time to is , the momentum at time is , and the momentum at time is , then:

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## External links

### Instructional video links

- Physclips by University of New South Wales -- choose and play Section 5.2