Forces are pushes or pulls that cannot be seen but can be detected through their effects such as making stationary objects move, changing the speed or direction of moving objects, slowing or stopping moving objects, and changing the shape of objects. There are different types of forces including gravitational, elastic spring, frictional, and magnetic forces. Gravitational force is the force of attraction between objects with mass. Elastic spring force stores energy when compressed or stretched and releases it to return the spring to its original shape. Frictional force slows and stops moving objects when they contact another surface. Magnetic force can be either attractive or repulsive depending on the object and magnet.

1. Forces

2. Going Back … A force is a PUSH or a PULL Forces cannot be seen How do we know they exist?

3. The Effects of a Force It can make a stationary object move It can make a moving object speed up It can change the direction a of a moving object It can slow down a moving object It can stop a moving object It can change the shape of an object

4. Different Types of Forces Gravitational force (gravity) Elastic spring force Frictional force (friction) Magnetic force

5. Gravitational Force Is there a force acting on the ball? Is the force of attraction a push or a pull? Will an object have any weight if there is no gravitational force acting on it?

6. Elastic Spring Force What happens to the spring after it is compressed or stretched, then released? Is the rubber band elastic? Is the modelling clay elastic?

7. Frictional Force Why did the coin slow down and stop? Friction is greater when on object is an a rough surface In what ways is friction useful to us? Friction can produce heat

8. Magnetic Force (P3 Revision) Magnetic force of attraction Magnetic force of repulsion Attraction -> pull Repulsion -> push