A man is standing on a spring balance. Reading of spring balance is $60 \mathrm{~kg} \mathrm{f}$. If man jumps outside balance, then reading of spring balance (A) First increase than decreases to zero (B) Decreases (C) Increases (D) Remains same

Spring balance is a device used to measure the weight of an object by balancing the force due to the object's weight with the force exerted by the spring. When an object is placed on a spring balance, it compresses the spring, and the reading depends on the equilibrium position of the spring, at which the spring force balances the object's weight. The change in the reading of a spring balance occurs due to a change in the object's weight or force exerted on the spring.

Initially, the man is standing on the spring balance, compressing it, and as a result, the spring force balances the weight of the man. At this moment, the reading is 60 kgf.

The man jumps off the balance. When he does that, he exerts an upward force on the spring balance as he pushes off to jump. This upward force momentarily exceeds his weight, temporarily increasing the total force acting on the spring.

Once the man jumps off and is no longer in contact with the spring balance, there is no weight acting on the spring balance, and it does not have to counter the man's weight. Therefore, the reading of the spring balance will change during and after the mans' action. Initially, when the man starts pushing off and exerts an upward force, the force on the spring balance increases, causing the reading to increase momentarily. However, as soon as he leaves the balance and is no longer exerting any force on it, the reading of the balance decreases, eventually reaching zero when the spring balance returns to its initial position (uncompressed). Hence the spring balance reading first increases and then decreases to zero.

Based on our analysis, the correct answer is option (A) - First, the reading will increase and then decreases to zero as the man jumps off the spring balance.