Mass vs. Weight
These two terms are often used interchangeably in daily life, but in science, they are very different.
| Feature | Mass | Weight |
|---|---|---|
| Definition | The amount of matter in an object. | The force with which Earth attracts an object. |
| Changeability | Constant everywhere (Earth, Moon, Space). | Changes based on gravity (Lighter on Moon). |
| SI Unit | Kilogram (kg) | Newton (N) |
| Measurement Device | Beam Balance | Spring Balance |
Note
Did you know? An object on the Moon weighs 1/6th of its weight on Earth because the Moon’s gravity is weaker. However, its mass (kg) remains exactly the same.
Measuring Weight: The Spring Balance
A spring balance measures weight by the stretching of a spring.
- Principle: The Earth pulls the object down.
- Action: This force stretches the spring.
- Reading: The extent of stretching corresponds to the weight (Force) in Newtons.
Reading a Spring Balance
To measure accurately, you must find the Least Count (the value of one small division).
- Example: If the range 0 to 1 N has 5 divisions, then 1 division = .