A spring balance is attached to the ceiling of a lift.
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
(a) 24N
(b) 74N
(c) 15N
(d) 49N.
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(a) : When lift is standing, W1 = mg
When the lift descends with acceleration a,
W2 = m (g – a)
Therefore, w2/w1 = m(g - a)/mg = (9.8 - 5)/9.8 = 4.8/9.8
or w2 = w1 x 4.8/9.8 = (49 x 4.8)/9.8 = 24N.
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