Forces

Forces are usually a push or a pull.
Forces are measured using a newtonmeter and the unit of force is Newtons.
Forces work in pairs - as you push down on a table the table pushes up with equal force.
When there is no change in velocity or shape of an object then the forces are balanced e.g. book on table
When there is a change in velocity or shape of an object then the forces are not balanced e.g. person falling through ice.
An example of a force is gravitational force. To work out the weight of an object (with gravity working on it) you use the following formula:
Weight (N) = mass (kg) x gravitational force (N/kg)
The main formula to use to work out forces is:
Force (N) = mass (kg) x acceleration (m/s/s)
OR F=ma