Question

A man of mass $80$ kg pushes a box of mass $20$ kg horizontally. The man moves the box with a constant acceleration of $2m/s^2$ but his foot does not slip on the ground. There is no friction between the box and the ground, whereas there is sufficient friction between the man's foot and the ground to prevent him from slipping.
Statement-1: The force applied by the man on the box is equal and opposite to the force applied by the box on the man.
and
Statement-2: Friction force applied by the ground on the man is $200$ N.

• A. Statement-1 is true, Statement-2 is true;
  Statement-2 is not the correct explanation of Statement-1.
• B. Statement-1 is false, Statement-2 is true.
• C. Statement-1 is true, Statement-2 is false.
• D. Statement-1 is true, Statement-2 is true;
  Statement-2 is the correct explanation of Statement-1.

Answer 1

The correct option is C Statement-1 is true, Statement-2 is false.

Force applied by the man on the box would be equal to the force applied by the box on the man as every action has an equal and opposite reaction.

Hence, force on man=$ma$ = $20\times 2=40N$

This would be equal to the frictional force on the man as their is no slipping happening between the ground and man.

Hence, statement-1 is true but statement-2 is false.