### Year 7 Physics

Introduction to Forces
Contact Forces
Non-Contact Forces
Levers
Wheels & Axles and Pulleys

# 8 | Summary

## Summary

• A force is something that causes an object to change its speed, direction or shape.
• An increase in speed is known as acceleration.
• A decrease in speed is known as deceleration.
• An object that returns to its original shape once a force is no longer acting on it is known as an elastic object.
• An object that retains its new shape once a force is no longer acting on it is known as an inelastic object.
• A force can be classified as a push, a pull or a twist.
• A push force is directed away from the source of the force.
• A pull force is directed towards the source of the force.
• A twist force involves rotation around a fixed point.
• Forces can also be classified as contact forces or non-contact forces.
• A contact force touches the object it is acting on.
• A non-contact force does not touch the object it is acting on.
• Forces have a magnitude and a direction.
• The magnitude of a force is measured in newtons, which have the symbol N.
• The direction of a force can be indicated using an arrow.