Question

The initial speed with which water strikes the ground in $m{s}^{-1}$ is:

• A. $10$
• B. $5$
• C. $5\sqrt{2}$
• D. $10\sqrt{2}$

Answer 1

The correct option is D $10\sqrt{2}$

Velocity of efflux for a given body = $(\frac{2gh}{1-\frac{a^2}{A^2}}{)}^{0.5}$ where "h" is the height from the ground , 'A' is the area of the tank and "a" is the area of the orifice .

now here "h" = 10m , a = ${10}^{-4}{m}^2$ , A = $\pi r^2$ = $\pi m^2$

so $(1-\frac{a^2}{A^2})$ is approximately = 1 in this case

so velocity of efflux in this case = $\left(2\right(10\left)\right(10){)}^{\frac{1}{2}}$ = $(200{)}^{0.5}$

so option (D) is correct