Contact and Non-Contact Forces/Effect of forces

what are Contact forces

Contact forces are forces that act between two objects that are physically touching each other.

When a contact force acts between two objects, both objects experience the same size force, but in opposite directions. This is Newton's Third Law of Motion.

Reaction force

An object at rest on a surface experiences reaction force. For example, a book on a table.

Tension

An object that is being stretched experiences a tension force. For example, a cable holding a ceiling lamp.

Friction

Two objects sliding past each other experience friction forces. For example, a box sliding down a slope.

Air resistance

An object moving through the air experiences air resistance. For example, a skydiver falling through the air.(this is a contact force)

Non-contact forces

Non-contact forces are forces that act between two objects that are not physically touching each other. Examples of non-contact forces include:

Magnetic force

A magnetic force is experienced by any magnetic material in a magnetic field.

Electrostatic force

An electrostatic force is experienced by any charged particle in an electric field.

Gravitational force

A gravitational force is experienced by any mass in a gravitational field.

Masses are attracted towards each other by gravitational force:

State the effect of forces on objects

Effect of Force	Example
Change speed	Car accelerates or brakes
Change direction	Football changes path mid-air
Change shape	Spring stretches
Start motion	Pushing a trolley
Stop motion	Braking a bike

elastic deformation

Elastic deformation is where an object returns to its original shape after the external force have been removed

What is inelastic deformation?

Inelastic deformation is a permanent change in shape of an object when external forces are applied, meaning it does not return to its original shape after those forces have been removed.