Question

Calculate the height through which a body of mass $0.5kg$ is lifted if the energy spent in doing so is $1.0J$. (Take $g=10m{s}^{-2}$)

• A. $2m$
• B. $0.2m$
• C. $20m$
• D. $0.4m$

Answer 1

The correct option is B $0.2m$

Energy spent equals the Work done against gravity while lifting.

Where, $W_{Ext}=\Delta U_{Gravitational}$

Change in potential energy of the body in lifting the height h is given by:

$\Delta U=mgh$

So, $1J=0.5\times 10m/s^2\times h$

$\Rightarrow h=1/5=0.2m$

Hence Option (B) is correct.