Chapter 7, Problem 53A

What will be the acceleration of recoil when a 60-kg person on rollerskates pushes against a wall with a force of 30 N?

To determine

The acceleration of recoil when a $60\text{-kg}$ person on roller-skates pushes against a wall with a force of $30\text{N}$ .

Answer to Problem 53A

  $0.2{\text{m/s}}^{\text{2}}$

Explanation of Solution

Given:

The mass of the person, $m=60\text{kg}$

The force with which he pushed against the wall, $F=30\text{N}$

Formula used:

As per Newton’s third law of motion, for every force exerted there is an opposite and equal reaction force.

And, according to Newton’s second law of motion, if the net force $F$ is applied to the mass $m$ , then the acceleration produced is given by,

  $a=\frac{F}{m}$

Calculation:

Considering the Newton’s third law of motion, the reaction force exerted on the person by the wall will be same as,

  $F=30\text{N}$

Then using Newton’s second law of motion, the acceleration of the recoil will be,

  $\begin{array}{c}a=\frac{F}{m}\\ =\frac{30}{60}\\ =0.2{\text{m/s}}^{\text{2}}\end{array}$

Conclusion:

Since, the acceleration of the recoil is $0.2{\text{m/s}}^{\text{2}}$ .