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A water cannon directs a jet of water towards a vertical wall. 300 kg of water hit the wall each minute. The water hits the wall horizontally with a velocity 20 m s–1. Assume the water falls vertically after hitting the wall.
What force does the water exert on the wall?A 100N B 200N C 3000N D 6000N
helpp!!!
Write down the values they've given you first.
Mass of water = 300 kg
each minute = every 60 seconds
final velocity = 20 ms^-1
They want the force, since we have mass, the formula we're going to use is F = ma.
We have the value of the mass, all we need is the acceleration.
a = v - u / t
Since the water hits every minute, that is 60 seconds between when it leaves the cannon and hits the wall.
a = v - u / 60
The water obviously starts from rest, before being fired out, so the initial velocity is 0.
You have the final velocity at which it hits the wall, which is 20 ms^-1/
a = 20 - 0 / 60
a = 20/60
a = 1/3 ms^-2, plug this value back into F = ma.
F = 300 kg * 1/3 ms^-2
F = 100 N, so your answer is A.
Hope that made sense!