A man is standing on a spring platform. The reading of spring balance is 60 kg wt. If the man jumps off the platform, then the reading of the spring balance will:

• Newton's third law of motion states that every action has an equal and opposite reaction.
• According to Newton's third law of motion, while jumping off a platform, when a man exerts force on the platform, the platform also exerts an equal and opposite force on the man that pushes the man off the platform.
• Therefore, we can say the man exerts an extra force on the springboard while jumping off.
• Hence the reading on the spring balance increases. But as soon as the man leaves the platform, the reading on the spring balance decreases to zero as no force is being applied to the spring balance.

Therefore, the reading on the spring balance will first increase and then decrease to zero.