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byahnoob
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Homework Statement
A block of mass m is connected to a massless rod and plunger of area A1 on a cylindric container of water. At
the bottom of the container there is a pipe that leads to an opening of area A2 where the water pours out at a
velocity v. The block starts at rest with the plunger a distance h from the bottom of the container.
A] What pressure does the block apply to the water? Only use A1 , m, and g in your answer.
B] What kinetic energy does the block have as water pours from the opening? Express your answer in terms of m, g, A1 , A2 , P0 , h, and ρ .
HINT* - solving for 1⁄2 v2 will get you very close to an expression for K.
[ATTACHED PICTURE OF PROBLEM]
Homework Equations
F = PA
Bernoulli's equation
KE = 1/2mv^2
The Attempt at a Solution
A] F = PA
mg = PA1
answer:
mg/A1 = P
B] Using Bernoulli's equation
P + pgh = P0 + 1/2pv^2
mg/A1 + pgh = P0 + 1/2pv^2
REARRANGE
(1/p)(mg/A1 + pgh + P0) = 1/2v^2
answer:
KE = 1/2mv^2 = (m/p)(mg/A1 + pgh + P0)
AM I CORRECT OR WRONG? I don't know how to get that A2 to the answer of part B