A body of mass 10 kg is hanging from a spring inside a lift. If the lift falls with an acceleration 10ms-2 then what will be the reading of spring balance:
Correct answer: A. Zero
- A. Zero
- B. 2.5 kg
- C. 5 kg
- D. 10 kg
Explanation
The reading of the spring balance in this case would be zero.When the lift falls with an acceleration of 10 m/s^2, the weight of the body remains the same (i.e., 10 kg) but the apparent weight of the body changes. The spring balance measures the apparent weight of the body, which is given by the difference between the weight of the body and the upward force exerted by the spring on the body. In this case, the upward force exerted by the spring is equal to the force of gravity acting on the body (i.e., its weight) plus the force required to provide the apparent weight due to the acceleration of the lift. This total force cancels out the effect of gravity, making the apparent weight zero.Therefore, the reading of the spring balance would be zero in this case.
This question appeared on the ETEA MDCAT 2017 paper, which you can sit online with every answer explained.
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