Newton’s 3rd Law
When body A exerts a force on body B, body B exerts an equal but opposite force on body A.
Force is measured in Newtons, N
Say What?
Newton’s 1st Law
If the forward and backward forces cancel out, a stationary object will remain stationary.
If the forward forces are greater than the backwards forces, a stationary object will begin to move forwards.
If the forward and backward forces cancel out, a moving object will continue to move with constant velocity.
If the forward forces are greater than the backward forces, a moving object will speed up.
If the backward forces are greater than the forward forces, a moving object will slow down.
Newton’s 2nd Law
The acceleration of an object increases when the force is increased but decreases when the mass is increased: but we rearrange this and use
Newton’s 3rd Law
Forces are created in pairs.
As you sit on the chair your weight pushes down on the chair, the chair also pushes up against you.
As the chair rests on the floor its weight pushes down on the floor, the floor also pushes up against the chair.
The forces have the same size but opposite directions.