Question

A stream of water flowing horizontally with a speed of 10m/s gushes out of a tube of crossectional area 10cm2 and hits a vertical wall nearby the force extracted the wall by impact of water (assume it rebounded)
1) 500N. 2) 20N. 3) 100N. ) 200N

Answer 1

Answer on question #51661, Physics, Mechanics — Kinematics — Dynamics

Question A stream of water flowing horizontally with a speed of 10m/s gushes out of a tube of crossectional area 10cm2 and hits a vertical wall nearby the force extracted the wall by impact of water (assume it rebounded) 1) 500N. 2) 20N. 3) 100N. ) 200N

Solution basic assumptions are:

Dynamic pressure can be found as

$p=\frac{\rho v^{2}}{2}$

where $\rho=1000kg/m^{3}$ is density and $v=10m/s$ is velocity. To find force we have to multiply it by area $S=0.001m^{3}$. And to take into account that stream is rebounded, we have to multiply whole thing by 2. Hence,

$F=2\cdot S\cdot\frac{\rho v^{2}}{2}=2\cdot 0.001\cdot\frac{1000\cdot 10^{2}}{2}=100\,N$

Answer is 3. 100N.