Weight and mass
Mass is how much matter something has (kg). Weight is the force of gravity pulling on that mass (newtons).
Key facts
- Weight = mass × gravitational field strength: W = m g.
- On Earth g is about 10 N/kg (9.8 more precisely).
- On the Moon g is about 1.6 N/kg, so you weigh about a sixth as much.
- Your mass stays the same everywhere.
Worked examples
Example 1
What does a 50 kg person weigh on Earth (g = 10 N/kg) and on the Moon (g = 1.6 N/kg)?
- Earth: W = 50 × 10 = 500 N
- Moon: W = 50 × 1.6 = 80 N
Answer: 500 N and 80 N