Step 1: Find the volume of water hitting the wall each second. The formula for flow rate (volume per second) is: Volume per second = Area × Velocity Here, Area =2×10−3m2 and Velocity =12ms−1 Volume per second =2×10−3×12=24×10−3m3∕s Step 2: Find the mass of water hitting the wall each second. To get the mass per second, multiply the volume flow by the density of water ( ρ=1000kg∕m3 ): Mass per second = Density × Volume per second =1000×24×10−3=24kg∕s Step 3: Calculate the force on the wall. Force is the change in momentum per second. The water hits the wall at velocity 12ms−1 and stops instantly. Force = Mass per second × Velocity =24×12=288N
