Question

A spring balance and a physical balance are kept in a lift. In these balances equal masses are placed. If now the lift starts moving upwards with constant acceleration, then

• A. The reading of spring balance will increase and the equilibrium position of the physical balance will disturb
• B. The reading of spring balance will remain unchanged and physical balance will remain in equilibrium
• C. The reading of spring balance will decrease and physical balance will remain in equilibrium
• D. The reading of spring balance will increase

Answer 1

Answer: (D)

The reading of spring balance will increase

Physical balance is based on comparison. So, even though the actual apparent weight increases but when compared with the standard weights, it will show the original reading.

For a mass weighed by spring balance, the mass experiences a psuedo force in the downward direction and hence, effective weight in the frame of reference of the lift increases.