Question

A bird is sitting in a large closed cage which is placed on a spring balance. It records a weight placed on a spring balance. It records a weight of 25 N. The bird (mass = 0.5kg) flies upward in the cage with an acceleration of $2m/s^{2}$. The spring balance will now record a weight of

• A. 24 N
• B. 25 N
• C. 26 N
• D. 27 N

Answer 1

Answer: (B)

25 N

Answer 2

Since the cage is closed and we can treat bird cage and air as a closed (Isolated) system. In this condition the force applied by the bird on the cage is an internal force due to this reading of spring balance will not change.