Chapter 4, Problem 4TS

Joshua has a mass of $60\text{kg}$ and stands next to a wall on a frictionless skateboard. If he pushes the wall with a force of $30\text{N}$, how hard does the wall push on him? Show that Joshua accelerates at $0.5\text{m}/{\text{s}}^2$ away from the wall.

To determine

The force exerted by wall on Joshua and the accelerationof Joshua is $0.5\text{m}/{\text{s}}^2$.

Answer to Problem 4TS

The force exerted by wall on Joshua is $30\text{N}$ and the acceleration of Joshua is $0.5\text{m}/{\text{s}}^2$.

Explanation of Solution

Given info:Mass of Joshua is $60\text{kg}$ and the force exerted by him on wall is $30\text{N}$.

The force exerted by Joshua on the wall is $30\text{N}$.Thus, according to Newton's third law the wall also exerts the force of on him but oppositein direction.

Write the expression for the acceleration.

$a=\frac{F}{m}$

Here,

$F$ is the force by him on wall

$m$ is the mass of Joshua

Substitute $30\text{N}$ for $F$ and $60\text{kg}$ for $m$ in the above expression to get $a$.

$a=\frac{30\text{N}}{60\text{kg}}$

$a=0.5\text{m}{\text{/s}}^2$

Conclusion:

Therefore, The force exerted by wall on Joshua is and the acceleration of Joshua is $0.5\text{m}/{\text{s}}^2$.