Chapter 12, Problem 86A

To determine

Work done by weight lifter.

Answer to Problem 86A

  $3439.8\text{ J}$

Explanation of Solution

Given:

Mass of barbell, $m=180\text{ kg}$

Height, $h=1.95\text{ m}$

Formula used:

  $U=mgh$

Here, U is potential energy, m is mass, g is acceleration due to gravity and h is height.

Calculation:

Work done in lifting the barbell will be equal to potential energy gained by the barbell.

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

Now, putting the value of m, g and h.

  $\begin{array}{c}U=180\times 9.8\times 1.95\\ =3439.8\text{ J}\end{array}$

Conclusion:

Therefore, work done in lifting the barbell is $3439.8\text{ J}$ .