No, a spring balance is not used to directly measure mass.
A spring balance measures the weight of an object, which is the force exerted on the object due to gravity. Weight is dependent on the local gravitational acceleration. Mass, on the other hand, is a fundamental property of an object and remains constant regardless of location.
Here's a breakdown:
- Mass: A measure of the amount of matter in an object. It is a scalar quantity and is measured in kilograms (kg) or grams (g).
- Weight: The force exerted on an object due to gravity. It is a vector quantity (has both magnitude and direction) and is measured in Newtons (N). Weight is calculated as: Weight (W) = mass (m) x acceleration due to gravity (g). The value of 'g' varies slightly depending on location.
A spring balance works by measuring the extension of a spring when an object is hung on it. The extension is proportional to the force applied, which is the weight of the object. The scale of the spring balance is usually calibrated to read the weight directly in Newtons or, more commonly, in units of mass (kg or lbs) assuming a standard value for gravitational acceleration (approximately 9.81 m/s² on Earth). This is why a spring balance can appear to be measuring mass, but it's actually measuring weight and inferring mass based on a known or assumed 'g'.
A beam balance (also known as an equal-arm balance or analytical balance) directly measures mass by comparing the mass of an unknown object to a known mass. This method is independent of gravity, so the reading represents the true mass.
| Feature | Spring Balance | Beam Balance |
|---|---|---|
| Measures | Weight | Mass |
| Principle | Extension of a spring | Comparison of masses |
| Gravity Dependent | Yes | No |
| Unit | Newtons (N), often calibrated in kg or lbs assuming standard 'g' | Kilograms (kg), grams (g) |
Therefore, while spring balances are often calibrated to display readings in units of mass, they inherently measure weight. A beam balance provides a direct measurement of mass.
