The aim of this activity is to understand weight, and be able to use the formula W = mg. Models of balls falling on the earth, the moon and in space, are used to show the dependence upon gravitational field. The operation of a spring balance (or newton balance) is also seen.

This item teaches:

• the definition of g as force per unit mass
• about the weight equation: weight = mass x gravitational field strength
• how weight would vary in different parts of the solar system
• the definition of weight