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

The correct option is D At first greater than $mg$, and later becomes equal to $mg$

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