Chapter 9, Problem 3A

Which requires more work, lifting a 10-kg load a vertical distance of 2 m or lifting a 5-kg load a vertical distance of 4 m?

To determine

To identify: The load that will requires more work to lift for the given specifications.

Answer to Problem 3A

Same work is required in lifting both the loads.

Explanation of Solution

Given :

Mass of first load, $m=10\text{ kg}$

Vertical distance of first load, $h=2\text{ m}$

Mass of second load, $m=5\text{ kg}$

Vertical distance of second load, $h=4\text{ m}$

Formula used :

According to work energy theorem wok done is equal to change in potential energy.

  $W=mgh$

Where, W is work done, m is mass and h is vertical distance.

Calculation :

Acceleration due to gravity, $g=9.8{\text{ m/s}}^2$

For first load substituting the value of m , g and h and solve.

  $\begin{array}{l}W=10\times 9.8\times 2\\ =196\text{ J}\end{array}$

For second load substituting the value m , g and h and solve.

  $\begin{array}{l}W=5\times 9.8\times 4\\ =196\text{ J}\end{array}$

Conclusion :

Therefore, same work is required in lifting both the loads.