Mass of a block via kinetic friction

[AnkhUNC]

[SOLVED] Mass of a block via kinetic friction

Homework Statement

In Fig, two blocks are connected over a pulley. The mass of block A is 5.9 kg and the coefficient of kinetic friction between A and the incline is 0.36. Angle θ of the incline is 43°. Block A slides down the incline at constant speed. What is the mass of block B?

http://edugen.wiley.com/edugen/courses/crs1650/art/qb/qu/c06/fig06_34.gif

Homework Equations

The Attempt at a Solution

OK so I'm unsure of how how to compute this question. I'm going to need to find the tension in this problem in order to find the mass of block two correct?

So for m1:
Fy = N-mg+(Tsin43-(Tsin133 [90+43 for the Fk force]*.36))

How do I solve for T here if I don't have a second equation to help me solve? There isn't a normal force on block B seeing as it is in the air so I couldn't impose the two to get rid of N right?

Fx = Tcos(43)-Tcos(133)*.36

Is this correct?

For m2:
Fy = T-mg
Fx = No movement

T>mg or block A would not be in kinetic friction.


Thanks,

 

[Doc Al]

So for m1:
Fy = N-mg+(Tsin43-(Tsin133 [90+43 for the Fk force]*.36))

How do I solve for T here if I don't have a second equation to help me solve? There isn't a normal force on block B seeing as it is in the air so I couldn't impose the two to get rid of N right?

Fx = Tcos(43)-Tcos(133)*.36

Is this correct?

This will be a bit easier to analyze using axes that are parallel and perpendicular to the plane, instead of horizontal and vertical.

For m2:
Fy = T-mg
Fx = No movement

T>mg or block A would not be in kinetic friction.

If T > mg, the blocks would accelerate.

 

[AnkhUNC]

Well that's sort of what I'm trying to do. I'm making the friction and tension south west and north east respectively. I kind of figured the way I set that up was incorrect but I haven't had to do two forces at the same time before.

 

[Doc Al]

For mass A, choose your x-axis as parallel to the incline and your y-axis as perpendicular. Then only the weight will need to be broken into components.