Question

A crane lifts a box of mass $400kg$ through a vertical height of $40m$. If acceleration due to gravity is $9.8m/s^2$, calculate the work done by the crane.

Answer 1

Step 1: Given data

Given that: -

Mass of box, $m=400kg$

Vertical height, $s=40m$

Acceleration due to gravity, $g=9.8m/s^2$

Work done, $W=?$ (To be calculated)

Step 2: Calculating the force required by a crane to lift the box

Applying, $F=m\times g$

By putting the given values in a formula, we get

$$\begin{gathered} F=400kg\times 9.8m/s^2 \\ \therefore F=3920N \end{gathered}$$

Step 3: Calculating the work done

Applying, $Workdone\left(W\right)=force\left(F\right)\times displacement\left(s\right)$

By putting the given values in a formula, we get

$$\begin{gathered} W=F\times s \\ W=3920N\times 40m \\ W=1,56,800J \end{gathered}$$

Hence, work done by the crane is $1,56,800J$