Force exerted normal to the plate

AI Thread Summary
A stationary flat plate is struck by a jet of water with a diameter of 50mm and a velocity of 18m/s, inclined at 25 degrees to the jet's axis. The angle between the water velocity and the normal to the plate is calculated to be 65 degrees. The normal force exerted on the plate is determined using the formula F = ρA(v)(v cos θ), resulting in two different answers: 278.7 N and 268.8 N. The discrepancy in results suggests a need to double-check arithmetic calculations. The discussion emphasizes the importance of verifying calculations in fluid dynamics problems.
foo9008
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Homework Statement


A jet of water , 50mm diameter , with a velocity of 18m/s , strikes a flat plate inclined at 25 degree to the axis of jet as shown in figure, Determine the normal force , P exerted on the plate when plate is stationary .

Homework Equations

The Attempt at a Solution


6ffCbqU.jpg

in the diagram attached , i found that the angle between the water velocity make an angle of 65 degree to the normal of the plate ,
so my ans is F = ρA(v)(v cos theta) = 1000(pi)( [(50x10^-3) / 2 ] ^2 ) (18^2)(cos 65) = 278.7 N , is my working correct ? i don't have the ans
 

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foo9008 said:

Homework Statement


A jet of water , 50mm diameter , with a velocity of 18m/s , strikes a flat plate inclined at 25 degree to the axis of jet as shown in figure, Determine the normal force , P exerted on the plate when plate is stationary .

Homework Equations

The Attempt at a Solution


6ffCbqU.jpg

in the diagram attached , i found that the angle between the water velocity make an angle of 65 degree to the normal of the plate ,
so my ans is F = ρA(v)(v cos theta) = 1000(pi)( [(50x10^-3) / 2 ] ^2 ) (18^2)(cos 65) = 278.7 N , is my working correct ? i don't have the ans
Your algebraic expression looks right but I don't get same answer (about 4% less). Check your arithmetic.
 
haruspex said:
Your algebraic expression looks right but I don't get same answer (about 4% less). Check your arithmetic.
my ans is 268.8N
 
foo9008 said:
my ans is 268.8N
That is what I get.
 
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