Forces

Velocity

The velocity of an object describes both the speed (distance divided by time) and direction of an object.

Measured in meters per second = m/s

Acceleration

The rate of change of velocity.
The acceleration of an object tells us how quickly the objects speed OR direction is changing.
Measured in meters per second squared = m/s²
 

Force

A push or a pull

Newton’s first law

An object will keep its same motion (stopped or moving at a constant speed is a straight line) unless an unbalanced force acts on the object.

Inertia

The property of an object that causes it to resist a change in its motion (stopped or moving at a constant speed in a straight line).

Newton’s third law

or every force object A exerts on object B, object B will exert an equal force but in the opposite direction on object A.

Resultant force or net force

The sum of all the forces acting on an object.

Newton’s second law

When a unbalanced force acts on an object it causes the object to accelerate a = F/m

OR
F = ma

Frictional force

The force which opposes the motion of an object.

Friction exists between any two surfaces which are in contact.
 

Normal force

A support force exerted by a surface on an object which is touching it.

A solid object stops another object from going through it by exerting a Normal force.

This is a type of resistive force.
 

Tension

A pull force which is experienced in ropes or strings

Compression

A push force which is able to deform (change the shape of) an object.
 

Gravitational force

The attractive force exerted on any object with mass.
 

Weight

The force which the earth exerts on any object which is on or near its surface.
More massive objects will have a bigger weight.
The weight depends on the object's mass and the planet's mass.
 

Mass

The amount of matter in an object.
Does not change on different planets.
 

Free fall

The motion of an object when the only force acting on an object is the gravitational force of the earth.