Laws Of Motion Question 241

Question: A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads 49 N, when the lift is stationary. If the lift moves downward with an acceleration of $ 5m/s^{2}, $ the reading of the spring balance will be [AIEEE 2003]

Options:

A) 49 N

B) 24 N

C) 74 N

D) 15 N

Show Answer

Answer:

Correct Answer: B

Solution:

When the lift is stationary $ W=mg $

therefore $ 49=m\times 9.8 $

therefore $ m=5kg. $ When the lift is moving downward with an acceleration $ R=m(9.8-a)=5[9.8-5]=24N $



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