Question

A man squatting on the ground gets straight up and stands. The force of reaction of ground on the man during the process is

• A. constant and equal to $mg$ in magnitude
• B. constant and greater than $mg$ in magnitude
• C. variable but always greater than $mg$
• D. at first greater than mg, and later becomes equal to $mg$

Answer 1

Answer: (D)

In the process of getting straight up and standing from squatting position, the man exerts a variable force $(F)$ on the ground to set his body in motion. This force is in addition to the force required to support his weight $(mg)$. Once the man is in standing position, $F$ becomes zero.