A Hailstorm Causes an Average Pressure of 1 $\times$ 10^-3 Kg,have an Average Velocity of 10 M/s Perpendicular to the 200-M²

Multiple Choice

A hailstorm causes an average pressure of 1.4 N/m² on the 200-m² flat roof of a house.The hailstones,each of mass 7.0 $\times$ 10^-3 kg,have an average velocity of 10 m/s perpendicular to the roof and rebound after hitting the roof with the same speed.How many hailstones hit the roof each second?

A) 4000
B) 2000
C) 1000
D) 10
E) 800