Answer:
0.9 N
Explanation:
The force exerted on an object is related to its change in momentum by:
[tex]F=\frac{\Delta p}{\Delta t}[/tex]
where
F is the force exerted
[tex]\Delta p[/tex] is the change in momentum
[tex]\Delta t[/tex] is the time interval
The change in momentum can be rewritten as
[tex]\Delta p = m(v-u)[/tex]
where
m is the mass
u is the initial velocity
v is the final velocity
So the formula can be rewritten as
[tex]F=\frac{m(v-u)}{\Delta t}[/tex]
In this problem we have:
[tex]\frac{m}{\Delta t}=0.030 kg/s[/tex] is the mass rate
[tex]u=-15 m/s[/tex] is the initial velocity
[tex]v=+15 m/s[/tex] is the final velocity
Therefore, the force exerted by the hail on the roof is:
[tex]F=(0.030)(+15-(-15))=0.9 N[/tex]
