Forces

Pushes and Pulls

You can make an object accelerate by pushing and pulling it. Your force is shown an arrow pushing (or pulling) the object.

eg: The engine of a car provides a force to push backwards on the road. Frictional forces from the road on the tyre push the car forwards.

Important situations:

• pushing and pulling
• lifting
• force of care engine
• attraction and repulsion by magnets and electric charges

Weight

This is the force of gravity acting on the object. It is usually shown by an arrow pointing vertically downwards from the object's centre of gravity.

Important situations:

• any object in a gravitational field
• less on the Moon

Friction

This is the force which arises when two surfaces rub over one another. If an object is sliding along the ground , friction acts in the opposite direction to its motion. If an object is stationary, but tending to slide - perhaps because it it on a slope - the force of the friction acts up the slope to stop it from sliding down. Friction always acts along a surface, never at an angle to it.

Important situations:

• pulling an object along the ground
• vehicles cornering or skidding
• sliding down a slope

Drag

This force is similar to friction. When an object moves through air, there is friction between it and the air. Also, the object has to push aside the air as it moves along.…