Chapter 5, Problem 2STP

To determine

To Choose: The correct option.

Answer to Problem 2STP

Option B: $F\text{=3}\text{.1}\times {\text{10}}^2\text{ N}$

Explanation of Solution

Given:

Mass of wooden pull cart, $m=30\text{ kg}$

Mass of each passenger, $M=90\text{ kg}$

Coefficient of statics friction, ${\mu }_s=0.15$

Formula used:

Friction force:

  $f={\mu }_s.N$

Where,

  ${\mu }_s=$ Coefficient of statics friction.

  $N=$ Normal reaction.

Calculation:

Normal reaction of the ground:

  $\begin{array}{c}N=\left(m+M\right)g\\ =\left(30+2\times 90\right)\times 9.8\\ =2058\text{ N}\end{array}$

Necessary force to move the cart:

  $\begin{array}{c}F=f\\ ={\mu }_s.N\\ =0.15\times 2058\\ =308.7\text{ N}\\ \text{=3}\text{.08}\times {\text{10}}^2\text{ N}\\ \approx \text{3}\text{.1}\times {\text{10}}^2\text{ N}\end{array}$

Conclusion:

Necessary force to move puller cart: $F\text{=3}\text{.1}\times {\text{10}}^2\text{ N}$