Question

A car of mass 2,000 kg is lifted up a distance of 30 m by a crane in 1 minute. A second crane does the same job in 2 minutes.

Find the amounts of work done by two cranes.

• A. $5.88\times {10}^{5}J,5.88\times {10}^{5}J$
• B. $5.88\times {10}^{5}J,2.94\times {10}^{5}J$
• C. $2.94\times {10}^{5}J,2.94\times {10}^{5}J$
• D. $1.076\times {10}^{6}J,5.88\times {10}^{5}J$

Answer 1

The correct option is A $5.88\times {10}^{5}J,5.88\times {10}^{5}J$

Work done by conservative force is $mgh$.

So irrespective of time work done will be same in both the cases and also work done is equal to energy consumed in form of fuel.

So work done by both the cranes is

$2000\times 30\times 9.81=5.88\times {10}^5$

So best possible answer is option A.