Types of Forces

Contact forces: These require physical

contact between objects.

Friction

Applied Forces

Normal Forces

Friction

• Friction is a force that slows motion when two objects

rub against each other

• Friction opposes motion

●rubbing both the hands
together to create heat

●a child sliding down through a
slide in a park

●a book sliding across a table

●a book resting on a table

●a car parked on a hill

●a ladder leaning against a
wall

●A moving car

●rolling a soccer or tennis ball

●a marble rolling on the floor

Applied Force

A force that is applied to an object by

another object or person

• when you push a door open

• kick a ball

• pull a drawer out

Normal Forces

Upward push of a surface on an object

that keeps the object from falling through.

● Books sitting on a table

● A person sitting on a tabletop

Non-contact forces: These act on objects
even if they are not physically touching.

Gravity

Magnetism

Magnetic Force

Attraction or repulsion between

magnetic poles.

• Magnet on a refrigerator
• MRI Machine
• A compass

Gravitational Force

The attraction between two objects

with mass, such as Earth pulling objects

toward its center.

● Rain falling to Earth
● Tides in the ocean

● Earth’s revolution around the sun