Question

Assertion: Spring balances show correct readings even after they had been used for a long-time interval.
Reason: On use for a long time, spring balances lose their elastic strength.
A. Both assertion and reason are correct and the reason is the correct explanation of the assertion.
B. Both assertion and reason are correct but the reason is not the correct explanation of the assertion.
C. The assertion is correct but the reason is incorrect.
D. The assertion is incorrect but the reason is correct.

Answer 1

Hint: When a spring balance is used for a long time, it develops elastic tiredness. So, it needs more time to reach its original position. Hence, the correct readings are not shown due to the continuous use of spring and do not recover their original position and that’s why it presents the wrong readings.

Complete step by step solution:
An object that can be deformed by a force and then return to its original shape after the force is removed is called a spring. There are many varieties of springs. Usually, a simple metal coil spring is widely used. The spring works on the principle of Hooke’s law where it says that stress is directly proportional to strain within the elastic limits.

When spring is loaded with a mass, the spring starts expanding downwards due to a deforming force. Due to this deformation, a restoring force comes into existence that acts opposite to the direction of deformation.

After this spring cycles through these deforming and restoring forces a lot of times, its elasticity decreases, and gradually the deformation becomes permanent since the restoring ability of the spring is decreased.

This inelastic spring, when loaded with the same mass considered earlier, does not cause the same movement (deform-restore) when compared to the original spring. This is why an old spring when used to measure a mass shows wrong readings.

Hence, option D is the correct answer.

Note: When we use the spring balance for a long time, it develops elastic fatigue in it. Elastic fatigue is the property of an object that loses its elasticity when it continuously undergoes deformation. Using the spring balance, we can estimate the weight of an object and further we can also calculate the acceleration due to gravity.