A ball is thrown vertically upwards from the ground with a speed of $25.2 {\mathrm{ms}}^{-1}$. How long does it take to reach its highest point and how high does it rise? (Take, $\mathrm{g} = 9.8 {\mathrm{ms}}^{-2}$)   

Given, upward velocity of ball = $25.2 {\mathrm{ms}}^{-1}$

Height attained by the ball,

                              $H=\frac{u^2}{2g}=\frac{25.2\times 25.2}{2\times 9.8}=32.4 \mathrm{m}$

Now, time taken by the ball to attain 32.4 m is

                             $t=\frac{u}{g}=\frac{25.2}{9.8}=2.57 \mathrm{s}$