Chapter 9, Problem 61RE

To determine

To find: The work done by the force of $5\text{pounds}$ .

Answer to Problem 61RE

The work done by the force of $5\text{pounds}$ is $\text{50}\text{foot-pound}$ .

Explanation of Solution

Given information:

The force is $F=5\text{pounds}$ .

The angles are $\theta =60°$ .

The horizontal displacement is $r=20\text{feet}$ .

Calculation:

The component of the force in the direction of the displacement is

  $F\cos 60°=\frac{F}{2}$

Write the expression for the work done.

  $W=\frac{F}{2}\times r$

Substitute the values in the above expression.

  $\begin{array}{c}W=\frac{5\text{pounds}}{2}\times 20\text{feet}\\ \text{=50}\text{foot-pound}\end{array}$

Therefore, the work done by the force of $5\text{pounds}$ is $\text{50}\text{foot-pound}$ .