What can a force do?
When a force acts on an object it can change the object's motion or its shape. A single force, or several forces together, can produce these effects of force.
Effects on motion
- Start moving: a force can make a still object begin to move, like kicking a ball.
- Stop moving: a force can bring a moving object to rest, like brakes stopping a bicycle.
- Speed up or slow down: a force can change how fast an object moves.
- Change direction: a force can make a moving object turn, like a footballer heading a ball.
Key idea
A force can change an object's speed, its direction of motion, or its shape. A larger force produces a bigger change on the same object.
Effect on shape
A force can also change the shape or size of an object by stretching, squeezing, bending or twisting it. Squeezing a sponge, stretching a rubber band, and bending a ruler are all examples. Some materials return to their original shape when the force is removed; others stay deformed.
Example
When you press modelling clay it changes shape and stays that way. When you stretch a rubber band and let go, it springs back to its original shape.
Remember
- Force can start, stop, speed up, slow down or turn an object.
- Force can also change an object's shape or size.
- A bigger force causes a bigger effect.