# Determine a formula for the acceleration of each block

1. Feb 1, 2007

### endeavor

1. The problem statement, all variables and given/known data
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 FT in teh cord in terms of m1, m2, and $$\theta$$; interpret your results in light of your answers to (a) and (b).

2. Relevant equations
3. The attempt at a solution

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:
$$m_1 g \sin \theta - F_{fk1} - T = m_1 a_1$$
$$T + m_2 g \sin \theta - F_{fk2} = m_2 a_2$$
$$F_{fk1} = \mu_1 N_1$$
$$F_{fk2} = \mu_2 N_2$$

2. Feb 1, 2007

### PhanthomJay

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?

3. Feb 1, 2007

### 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.

4. Feb 1, 2007

### PhanthomJay

Yes, that is correct.