10000 small balls, each weighing 1 g, strikes 1 cm2 of area per second with a velocity 100 ms-1 in a normal direction and rebound with the same velocity. The value of pressure on the surface will be

In 1 cm2 area, 104 balls are striking per second. Therefore, in 1 m2 area, 108 balls will strike per second.Change in momentum of each ball per second will be 2 mu.∴  Pressure =FA=N(Δp/Δt)A=n×2m×u∵n=NAΔt=108                      = 108×2×10-3×100                       = 2×107 Nm-2