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Edwardo_Elric
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Homework Statement
A problem in engineering mechanics:
The blocks shown in the figure are connected by flexible inextensible cords passing over frictionless pulley. At Block A the coefficients of friction are Ms = 0.30 and Mk = 0.20 while at Block B they are Ms = 0.40 and Mk = 0.30. Compute the magnitude and direction of the friction force acting on each block.
the answer is Friction at A = 48lb
Friction at B = 36lb
Homework Equations
R is along the angle of friction w/c has two components:
Normal force at the vertical
Friction at the horizontal
The Attempt at a Solution
I do not know how to approach the problem since there are two given coefficient of friction and it seems very confusing...
however i tried solving at block A using the coefficient of kinetic friction at A = 0.20:
F = friction
R = the force along the angle of friction
the angle of friction here lies along with R which is the coefficient of friction
tan(theta) = 0.20
theta = 11.3 degrees
so i used sine law:
[tex]\frac{\sin{79}}{300} = \frac{\sin{53}}{R}[/tex]
R = 244lb
R has two components: the normal force N and the friction F
F = (244lb)(sin(11.3))
F = 48lb <<< at A
i am not so sure about this..
can u give some hints its very confusing
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