Bird in Spring Balance – Rankers Physics

Third Law of Motion: Practice Problem & Solution

Assertion (A): An air tight cage in which a bird is sitting, is suspended from a spring balance. If the bird starts flying upwards with some acceleration, then the reading of the balance will increase. Reason (R): The weighing machine measures the actual weight of a body.  
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Third Law of Motion. Understanding the underlying formula is key to arriving at the correct answer below:

When the bird flies up with acceleration, it pushes more air downwards, increasing the effective weight measured. So (A) is true. A weighing machine measures apparent weight, not always actual weight. Thus (R) is false.

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