# Physics

HideShow resource information

## Resultant force

An object may have several different forces acting on it, which can have different strengths and directions. But they can be added together to give the resultant force. This is a single force that has the same effect on the object as all the individual forces acting together.

1 of 6

## Zero resultant force

When all the forces are balanced, the resultant force is zero. In this case:

• A stationary object remains stationary

• A moving object keeps on moving at the same speed and in the same direction

2 of 6

## Non - zero resultant force

When all the forces are not balanced, the resultant force is not zero. In this case, an object accelerates in the direction of the resultant force. This means that:

• A stationary object begins to move in the direction of the resultant force

• A moving object speeds up, slows down or changes direction depending on the direction of the resultant force

3 of 6

## Size of the force

An object will accelerate in the direction of the resultant force. The bigger the force, the greater the acceleration. Doubling the size of the (resultant) force doubles the acceleration.

4 of 6

## The mass

An object will accelerate in the direction of the resultant force. A force on a large mass will accelerate it less than the same force on a smaller mass. Doubling the mass halves the acceleration.

5 of 6

## Calculating acceleration

a = F ÷ m

• F is the resultant force in newton’s, N

• m is the mass of the object in kilograms, kg

• a is the acceleration of the object in metres per second squared, m/s2

6 of 6