Question

A man of $60$ kg gains $1000$ cal of heat by eating $5$ mangoes. His efficiency is $56\%$. To what height he can jump by using this energy?

• A. $4m$
• B. $20m$
• C. $28m$
• D. $0.2m$

Answer 1

The correct option is A $4m$

E#nergy stored by the men $=1000cal$

we know that

Efficiency $=\frac{workdone}{storedenergy}$

$\Rightarrow \left(stored\right)\left(Efficiency\right)=workdone$

$workdone=\left(\frac{56}{100}\right)\left(1000\right)cal$

$\Delta w=\left(\frac{56}{100}\right)\left(1000\right)\left(4.184\right)J$

$\Delta w=1243.04J$

AS only gravitational force is acting on him?

$\Delta w=\Delta PE$ gravitational

$\Delta PE$ gravitation $=mgh$

$\Rightarrow \Delta w=mgh$

$\Rightarrow \frac{2343.04}{(2\times 30)\left(9.8\right)}=l$

$h=3.985\Rightarrow h=4m$

Option $A$ is correct