A pressure-pump has a horizontal tube of cross-sectional area 10 cm 2 for the outflow of water at a speed of 20 m s - 1 . The force exerted on the vertical wall just in front of the tube which stops water horizontally flowing out of the tube, is: [given : density of water = 1000 kg m - 3 ]

Step-by-step solution

Volume of water coming out of the pipe per sec = A v = 10 × 10 - 4 × 20 = 0 . 02   m 3   s - 1 Mass of water hitting the wall per second m = 0 . 02 × 10 3 = 20   kg   s - 1 As the water hits the wall normal to the wall and stops, the change of momentum of water hitting the wall is = m 0 - - v = m v = 20 × 20 = 400   kg   m   s - 2 Since, the change of momentum obtained is per unit time, it is same as the force. Thus, the force acting on the wall by water = forc