Question

A bird is in a wire cage hanging from a spring balance. The reading of the balance is taken when the bird is flying about in the cage and when the bird is at rest in the cage. The first reading will be:
A) Much greater than the second.
B) Greater than the second.
C) Less than the second.
D) Same as the second.

Answer 1

Hint: Bird flying in the cage isn't the same as the bird resting in the cage. Bird flying either in the cage or outside the cage means that there is no pressure of the bird's weight on the cage in comparison to the bird resting in the cage.

Complete step by step solution:
Here, the first reading is taken when the bird is flying in the cage and the second reading is taken when the bird is at rest. In the first reading the total mass of the whole system (cage + bird) is just the cage and not the bird as it is flying. In the second reading the total mass of the whole system would be the mass of the cage and the mass of the bird since it is resting on the cage. The spring balance will show greater deflection in the second case in comparison to the first case as in the second case the spring will stretch greater than the first case.

Final Answer: Option “C” is the correct option. The first reading will be less than the second reading in the spring balance.

Note: Here one needs to clearly explain the two scenarios that are being mentioned in the question. In the first case the bird is flying inside the cage and the second case in which the bird is resting on the cage. Explain the difference between both the scenarios.