Determine a formula for the acceleration of each block

[endeavor]

Homework Statement

For two blocks, connected by a cord and sliding down the incline shown in the figure, describe the motion (a) if $$\mu_1 < \mu_2$$, and (b) if $$\mu_1 > \mu_2$$. (c) Determine a formula for the acceleration of each block and the tension F_T in the cord in terms of m₁, m₂, and $$\theta$$; interpret your results in light of your answers to (a) and (b).

Homework Equations

The Attempt at a Solution

http://img407.imageshack.us/img407/5930/chp5pro22nd5.th.png
I need help on part c.

I got two equations in three unknowns ($$T, a_1, a_2$$), and I don't know what to do:
$$m_1 g \sin \theta - F_{fk1} - T = m_1 a_1$$
$$T + m_2 g \sin \theta - F_{fk2} = m_2 a_2$$
$$F_{fk1} = \mu_1 N_1$$
$$F_{fk2} = \mu_2 N_2$$

 

[PhanthomJay]

Homework Statement

For two blocks, connected by a cord and sliding down the incline shown in the figure, describe the motion (a) if $$\mu_1 < \mu_2$$, and (b) if $$\mu_1 > \mu_2$$. (c) Determine a formula for the acceleration of each block and the tension F_T in the cord in terms of m₁, m₂, and $$\theta$$; interpret your results in light of your answers to (a) and (b).

Homework Equations

The Attempt at a Solution

http://img407.imageshack.us/img407/5930/chp5pro22nd5.th.png
I need help on part c.

I got two equations in three unknowns ($$T, a_1, a_2$$), and I don't know what to do:
$$m_1 g \sin \theta - F_{fk1} - T = m_1 a_1$$
$$T + m_2 g \sin \theta - F_{fk2} = m_2 a_2$$
$$F_{fk1} = \mu_1 N_1$$
$$F_{fk2} = \mu_2 N_2$$

If the blocks move together with tension in the cord, their accelerations are equal. What if the tension in the cord is negative under this assumption?

 

[endeavor]

Oh I see...
So under the conditions of part (a), a₁ = a₂. And under the conditions of part (b), there is no tension. So now there's only two unknowns in two equations.

 

[PhanthomJay]

Oh I see...
So under the conditions of part (a), a₁ = a₂. And under the conditions of part (b), there is no tension. So now there's only two unknowns in two equations.

Yes, that is correct.