Question

A bird is placed on a perch in a large closed box that is sitting on spring scale. What will happen to the scale reading when (a) the bird jumps off the perch, (b) the flying, (c) the bird lights on the perch again?

Answer 1

a) When the bid jumps off, the scale reading will increase at that moment because the bird pushes down on the cage while jumping.

b) When the bird is flying, its weight is balanced by the force it exerts on the air inside the box. Now, as the air is pushed down by the bird, it (air) exerts a force on the floor of the cage equal to weight of the bird. So the reading of the scale is equal to weight of the bird.

c) When the bird again sits on the perch, the scale again reads equal to weight of the bird.

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