Dureing a heavy rain hailstones of average size 1.0 cm in diameter fall with an average speed of 20 m/s. Suppose 2000 hailstones stgrike every square meter of a `10mxx10m` roof perpendicularly in one second and assume that the hailstones do not rebound. Calculate the average force exerted by the falling hailstones n the roof. Density of a hailstone is `900 km/s^3`

Explanation

`d=1, cm, v=20 m/s,
`u=0, p=900 kg/m^3`
`0.9 gm/cm^3`
`volume=(4/3)pir^3`
`=4/3pi(0.5)^3[=0.5238 cm^3`
`:. Mass =up=0.5238xx0.9`
`:. Mass of 2000 halistone`
`=2000xx0.4714=947.857`
`:. ` rate of change of momentum per unit area
`=947.857xx2000`
`=19N/m^2`
`:.` total force exerted
`=19xx100=1900N`