A boy having a mass of 60 kg, holds in hand a school bag of weight 40 N. With what force the floor will push up on his feet ? \[\text{(g }=\text{ 1}0\text{ m}/{{\text{s}}^{\text{2}}})\]
A) 100 N
B) 600 N
C) 640 N
D) 64 N
Correct Answer:
C
Solution :
Total force acting on boy bag system, is given by F = weight of boy + weight of bag F = 60 g + 40N \[\Rightarrow \] F = 60 \[\times \] 10 + 40 = 640N From Newtons third law, to every action there is an equal and opposite reaction. Therefore, the floor will push on his feet with a force of 640 N.