RRB Paramedical Staff Nurse Model Paper 3

Velocity at the time of striking the floor,
$\mathit{u}=\sqrt{2\mathit{g}\mathit{h}}=\sqrt{2\times 9.8\times 10}=14\mathit{m}/\mathit{s}$ (-ve since downwards)
Velocity with which it rebounds.
$\mathit{v}=\sqrt{2\mathit{g}{\mathit{h}}_2}=\sqrt{2\times 9.8\times 2.5}=7\mathit{m}/\mathit{s}$ (+ve since upwards)
$\therefore$ Change in velocity $△\mathit{v}=7-\left(-14\right)=21\mathit{m}/\mathit{s}$
$\therefore$ Acceleration $=\frac{∆\mathit{v}}{∆\mathit{t}}=\frac{21}{0.01}=2100\mathit{m}/{\mathit{s}}^2$ (upwards since positive)