- #1
fayan77
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Homework Statement
I am after PC - PA
However I must do so without breaking into components. My problem has different values
L=3
H=4
SG=1.2
downward a = 1.5g
horizontal a = 0.9g
and my coordinate is conventional positive y up and positive x to the right
cos##\theta## = 3/5
sin##\theta## = 4/5
Homework Equations
- ##\frac {\partial} {\partial l}## (p+##\gamma##l) = ##\rho##a
- ##\nabla p## = ##\rho##a
The Attempt at a Solution
a = 0.9g##\hat i## -1.5g##\hat j##
therefore,
- ##\frac {dp} {dl}##-##\gamma## = ##\rho##(0.9g##\hat i## -1.5g##\hat j##)
where dp = PC - PA
dl = 5 because of the 3,4,5 triangle
and in order to get rid of (i hat and j hat) i use triangle relationship and project 0.9g##\hat i## to l direction using 0.9g(3/5) and -1.5g(4/5)
therefore,
- (PA - PC) / 5 = ##\rho##(0.9g(3/5)-1.5g(4/5)) + ##\gamma##
PC - PA= -5##\rho##g(.9(3/5)-1.5(4/5)+1)
PC - PA= not correct answer
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