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.

(Image: Teemu Tretjakov, Adobe Stock)