Average pressure from rain falling on a circular region

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clovergogo
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Homework Statement


rain is falling normally on a circular region of radius 25cm at a rate of 1.2gs-1
suppose the velocity of each raindrop just before it reaches the region is 10cms-1
and the collision between each raindrop and the region is perfectly elastic
find the avg pressure exerted on the region

take g=9.8ms-1


Homework Equations



P= F/A

The Attempt at a Solution



momentum, then the Pressure
is it ...P = (0.0012X10+0.0012X9.8) / 0.25^2 pi??
 

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clovergogo said:

Homework Statement


rain is falling normally on a circular region of radius 25cm at a rate of 1.2gs-1
suppose the velocity of each raindrop just before it reaches the region is 10cms-1
and the collision between each raindrop and the region is perfectly elastic
find the avg pressure exerted on the region

take g=9.8ms-1

Homework Equations



P= F/A

The Attempt at a Solution



momentum, then the Pressure
is it ...P = (0.0012X10+0.0012X9.8) / 0.25^2 pi??
If the collisions are perfectly elastic, what is the change in momentum of a raindrop of mass m striking this area?

Now take N such raindrops every second such that Nm = 1.2 g. What is the total change in momentum of the raindrops every second? How is that change in momentum every second related to the force imparted to the circular area? What is that force/unit area?

AM
 
can i take t=1
then mv-mu/t = F can be count
then mass = 1.2 X 1
then Pressure (P) can be count
 
clovergogo said:
can i take t=1
then mv-mu/t = F can be count
then mass = 1.2 X 1
then Pressure (P) can be count

If you use the units and parentheses properly, the method will work. What is u if the collision is perfectly elastic?

ehild