The spring scale is a tool that measures the mass and gravity of an object using the spring’s elastic force.

The spring of this scale is lengthened by gravity and shortened by elasticity.

You can find out the gravity (or mass) of an object by reading the scale at the point where gravity and elastic force balance.

Try the slide to change the mass of the object.

If you want to know the magnitude and direction of gravity and elasticity, check the box below.

## Measuring limit of spring scale

All springs have an ‘elastic limit’. If it is overstretched, it loses its original elasticity and cannot be restored.

Therefore, most spring scales are built to prevent any increase above a certain limit to protect the spring inside.

Click the radio button to switch to a different spring scale.

If it does not move in the state of maximum value, replace it with another scale with a more large range.

Conversely, if the range is too wide, it may difficult to detailed measuring. After all, it is better to choose a suitable measuring range depending on the situation.

## Mass and gravity

All objects on the ground receive force towards the center of the earth (= gravity).

Gravity is a force proportional to the mass of an object. On the surface we live on, this proportionality constant becomes ‘gravity acceleration’. Gravitational acceleration is often known by the number ‘9.8’.

Gravity(N) = 9.8 × mass(kg)

If you look closely at the spring scale, you can see that the scales on the left and right scales are different. Moreover, the scales do not fit each other. This is because the force increases by 9.8N each time an object’s mass increases by 1kg.