# Newton's Second Law (including inertia)

I can explain what the equation F = m × a means and use it to carry out calculations.

# Newton's Second Law (including inertia)

I can explain what the equation F = m × a means and use it to carry out calculations.

## Lesson details

### Key learning points

- Resultant force = mass × acceleration, F = m × a.
- An object that is thrown in the air experiences a constant gravitational force towards the centre of the Earth.
- An object that is thrown in the air is constantly accelerating towards the centre of the Earth.
- Inertial mass is a measure of how hard it is to change the velocity of an object.
- Inertial mass = force ÷ acceleration, m = F ÷ a.

### Common misconception

When applying the equation F = m × a, pupils may take F to be any one of the forces acting on the object, rather than specifically the resultant force.

Provide some more complex examples, in which forces act in opposite directions, so pupils are required to work out the resultant force in preparation for completing calculations.

### Keywords

Resultant force - The overall effect of the forces acting on an object.

Acceleration - Caused by a resultant force and results in a change in speed and/or direction of movement.

Mass - The amount of matter in an object, measured in kilograms (kg).

Inertial mass - The mass determined by Newton’s Second Law of Motion; m = F ÷ a.

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

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## Starter quiz

### 6 Questions

mass -

kilograms

displacement -

metres

velocity -

metres per second

acceleration -

metres per second squared

force -

newtons

## Exit quiz

### 6 Questions

resultant force -

The overall effect of the forces acting on an object.

acceleration -

A change in velocity caused by a resultant force.

inertial mass -

The mass of an object based on how it accelerates when a force acts.