force

definition

force is a push or a pull that changes a state of motion of a body

force can have 5 different affects

1. it can create motion

2. it can cause acceleration

3. it can cause deceleration

4. it can cause a change in direction

5. it can cause a change in shape

vertical forces

weight- the gravitational pull that the earth exerts on a body and always acts downwards from a bodys centre of mass

reaction- is the equal and opposite force exerted by a body in response to the action placed upon it and it acts upwards from a bodys point of contact with the surface

horizontal forces

friction- is the force that opposes motion of two surfaces in contact and it usually acts in the same direction as motion from the point of contact with the sliding surface

air resistance- is a force that opposes the motion of a body it extends against the direction of motion from the centre of mass

what is friction affected by

1. roughness of the ground surface

2. roughness of the contact surface

3. temperature

4. size of normal reaction

what is air resistance affected by

1. velocity

2. shape

3. frontal cross sectional area

4. smoothness of surface