- #1
oreosama
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Homework Statement
blocks A B AND C are connected as show. block A and B have the same mass "m" and the coefficient of kinetic friction between each block is uk. block C descends with constant velocity. use 30 degrees for the angle of the incline.
given m, uk
find
a.
tension in rope between blocks A AND B
b.
mass of block C
c.
if the rope connected to block A is cut, determine the accel of block C
The Attempt at a Solution
http://i.imgur.com/KJsro.png
FAx = T1 - uk*N1 = 0
FAy = N1 - mg = 0
FBx = T2 - T1 - uk*N2 = 0
FBy = N - mg*cos(30) = 0
FCy = mc*g - T2 = 0
a.
N1 = mg -> T1 = uk*mg
b.
N2 = mg*cos(30) - > T2 = uk*mg + uk*mg*cos(30)
mc*g - ( uk*mg + uk*mg*cos(30) ) = 0
mc = uk*m + uk*m*sqrt(3)/2
I think these are right(confirm pls)
c is what confuses me but my attempt:
FBx = T2 - uk*N2 - g*sin(30) = 0
FBy = N2 = mg*cos(30)
FCy = mc*g - T2 = mc*a
T2 = uk*mg*cos(30) + g*sin(30)
a = (mc * g - T2) / mc * g
(uk*m + uk*m*sqrt(3)/2 - uk*m*sqrt(3)/2 + 1/2 ) / uk*m + uk*m*sqrt(3)/2 (g should cancel out)
is this all right? thanks for any help.