Chapter 4, Problem 1OQ

A 150-kg football player collides head-on with a 75-kg running back. During the collision, the heavier player exerts a force of magnitude F_Aon the smaller player. If the smaller player exerts a force F_Bback on the heavier player which response is most accurate?

   $\begin{array}{l}A.F_B=F_A\\ B.F_B<F_A\\ C. F_B>F_A\\ D. F_B=0\end{array}$

E. We need more information

To determine

A $150\text{kg}$ football player collides head-on with a $75\text{kg}$ running back. During the collision, the heavier player exerts a force of magnitude $F_A$ on the smaller player and the comparison of the magnitude of force between heavier lighter and heavier player.

Answer to Problem 1OQ

Solution: Both heavier player and lighter player exert force, each is equal in magnitude and opposite in direction. Hence option (A), $F_A=F_B$ is the correct answer.

Explanation of Solution

Newton’s third law of motion states that for every action, there is an equal and opposite reaction. Force exerted by a heavier player on the lighter player is an action-reaction pair to force exerted by a lighter player on the heavier player. So, both forces have the same magnitude but opposite in direction. Hence, option (A) is the correct option.

Conclusion:

Two objects exert equal and opposite force on each other, it does not matter which is lighter and which is heavier.