A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads 49N,
A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads 49N, When the lift is stationary. If the lift moves downward with an acceleration of 5m/s2, the reading of the spring balance will be:
(1) 24N
(2) 74N
(3) 15N
(4) 49N
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1 Answers
(1) The reading of the spring balance is 24N.
Explanation:
When lift is stationary,
W1 = mg
When the lift descends with acceleration a,
W2 = m(g – a)
W2/W1 = (g – a)/g
= (9.8 - 5)/9.8 = 4.8/9.8
W2 = W1 x (4.8/9.8)
= 49 x (4.8/9.8)
= 24 N
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