Question

A stream of water flowing horozintally with a speed of $15m{s}^{-1}$ gushes out of a tube of cross-sectional area ${10}^{-2}{m}^2$ and hits a vertical wall nearly. The force exerted on the wall by the impact of water assuming it does not rebound is

• A. $2.25\times {10}^{3}N$
• B. $2.5\times {10}^{3}N$
• C. $3.0\times {10}^{3}N$
• D. $35\times {10}^{3}N$

Answer 1

The correct option is A $2.25\times {10}^{3}N$

Velocity of flowing water $v=15m/s$

Area of tube $A={10}^{-2}{m}^2$

Density of water $\rho =1000kg/m^3$

So, rate of mass of water flowing $\frac{dm}{dt}=\rho Av=1000\times {10}^{-2}\times 15=150kg/s$

Force exerted on wall $F=\frac{dm}{dt}\times v=150\times 15=2.25\times {10}^{3}N$