FORCES

Definition

A push or a pull that one object exert on another

Effects of forces

Start or stop the motion of an object

Change the size and shape of an object

Increase or decrease the speed of a moving

Change the direction of motion of a moving object

Cannot be seen but the effects can be seen
and felt

Affects speed and distance travelled

Size of force applied is proportional to distance and speed of object

Greater force applied , greater distance travelled

Affects speed and distance travelled

Forces of nature

Useful

Harmful

Help to do work

Cause destruction

Wind turns windmill

Water turns water wheels

Volcano eruption šŸŒ‹

Tsunami or tidal waves

Forces of nature

Friction ( frictional force )

Characteristics

Exists between surfaces that are rubbing against each other

Reduces speed of moving objects

Produces heat

Opposes motion

Rougher surfaces

Greater friction

Produces more heat

Uses of friction

Allows us to control movement

Reduces slipping

Produces heat

Problem caused by friction

Wear and tear

Machines work less efficiently

Make things overheat

Object move slowly

Methods to reduce friction

Putting lubricant

Rollers , ball bearings and wheels

Streamlined body

Elastic Spring Force

Change shape when a force acts on them but will return
to original shape

When an object is stretched or compressed, it exerts
a force on the object stretching or compressing it

Gravity

Force between Earth and all objects

All objects have the same amount of gravitational force

Affected by

Difference

Magnetic force

Definition

Weight is the amount of gravitational force acting on an object.

Mass is the amount of matter in an object

Force that is exerted by magnets and magnetic materials

Attraction

A pulling force

Causes magnets to attract magnetic materials

Causes magnets to attract unlike poles of other magnets

Can use for testing if an object is a magnetic material

Cannot use to test if an object is a magnet

Repulsion

Can be used to test if an object is a magnet or a magnetic material

A pushing force

Causes magnets to repel like poles of other magnets