Question

A car of mass $2,000kg$ is lifted up a distance of $30m$ by a crane in $1minute$. A second crane does the same job in $2minutes$. Find the amounts of fuel consumed 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. $1.076\times {10}^{5}J,5.88\times {10}^{5}J$

Answer 1

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

Here, the amount of fuel is the amount of energy used. The energy is the potential energy and it does not depend on time. So for both cranes, the potential energy will be same.

Thus, potential energy $PE=mgh=2000\times 9.8\times 30=5.88\times {10}^{5}J$