A 2.00kg aluminum block and a 6.00kg copper block are connected by a light strin

Question

A 2.00kg aluminum block and a 6.00kg copper block are connected by a light string over a frictionless pulley. The two blocks are allowed to move on a fixed steel block wedge of angle 30.0 degrees. If the coefficient of kinetic friction between aluminim and steel is 0.47 and the coefficient of kinetic friction between copper and steel is 0.36, determine a) the acceleration of the two blocks and b) the tension on the string.

I know the answer to a) 0.24m^2 and b) 9.7N, I just don't know how to get to these answers.

Explanation / Answer

aluminum

T - u* Mal*g = Mal*a

T = u* Mal*g + Mal*a

for copper

Mc*g*sin30 - T - u*Mc*g*cos30 = Mc*a

Mc*g*sin30 - (u* Mal*g + Mal*a) - u*Mc*g*cos30 = Mc*a

Mc*g*sin30 - u* Mal*g - Mal*a - u*Mc*g*cos30 = Mc*a

Mc*g*sin30 - u* Mal*g - u*Mc*g*cos30 = Mc*a + Mal*a

(6*9.8*sin30) -(0.47*2*9.8)-(0.36*6*9.8*cos30) = a*(2+6)

a = 0.24 m/s^2

--------------------------

b) T = u* Mal*g + Mal*a

T = (0.47*2*9.8)+(2*0.24) = 9.7 N

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