A spring balance is attached to the ceiling of lift. A man hangs his bag on the string and the balance reads 49 N, when the lift is stationary. If the lift moves downwards with an acceleration of 5 ms-2. The reading of the spring balance would be

Question

A spring balance is attached to the ceiling of lift. A man hangs his bag on the string and the balance reads 49 N, when the lift is stationary. If the lift moves downwards with an acceleration of 5 ms-2. The reading of the spring balance would be (A) 24 N (B) 74 N (C) 15 N (D) 49 N

Tardigrade Admin · Accepted Answer

When the lift is stationary R=m g 49=m × 9.8 m=(49/9.8) kg =5 kg If a is downward acceleration of lift. then, R=m(g-a) R=5(9.8-5)=24 N

Q. A spring balance is attached to the ceiling of lift. A man hangs his bag on the string and the balance reads $49 N$ , when the lift is stationary. If the lift moves downwards with an acceleration of $5 m s^{- 2}$ . The reading of the spring balance would be

24 N

74 N

15 N

49 N

When the lift is stationary
$R = m g$
$49 = m \times 9.8$
$m = \frac{49}{9.8} k g = 5 k g$
If $a$ is downward acceleration of lift. then,
$R = m (g - a)$
$R = 5 (9.8 - 5) = 24 N$

Q. A spring balance is attached to the ceiling of lift. A man hangs his bag on the string and the balance reads 49N, when the lift is stationary. If the lift moves downwards with an acceleration of 5ms−2. The reading of the spring balance would be