Question

A stream of water flowing horizontally with a speed of 15 m s^–1 gushes out of a tube of cross-sectional area 10^–2 m², and hits a vertical wall nearby. What is the force exerted on the wall by the impact of water, assuming it does not rebound?

Answer 1

Speed of the water stream, v = 15 m/s
Cross-sectional area of the tube, A = 10^–2 m²
Volume of water coming out from the pipe per second,
V = Av = 15 × 10^–2 m³/s
Density of water, ρ = 10³ kg/m³
Mass of water flowing out through the pipe per second = ρ × V = 150 kg/s

The water strikes the wall and does not rebound. Therefore, the force exerted by the water on the wall is given by Newton’s second law of motion as: