Question

a stone is thrown with intial velocity of 4.9m/s from bridge in vertically upward direction.it falls down in water after 2sec.the height of the bridge is

Answer 1

$$\begin{gathered} \mathrm{From}\mathrm{the}\mathrm{equations}\mathrm{of}\mathrm{motion},\mathrm{the}\mathrm{expression}\mathrm{for}\mathrm{height}\mathrm{of}\mathrm{the}\mathrm{bridge}\mathrm{is} \\ \mathrm{h}=-\mathrm{ut}+\frac{1}{2}{\mathrm{gt}}^2 \\ =-\left(4.9\times 2\right)+\left(\frac{1}{2}\times 9.8\times 2^2\right) \\ \mathbf{}\mathbf{}\mathbf{=}\mathbf{9}\mathbf{.}\mathbf{8}\mathbf{}\mathbf{m} \end{gathered}$$