# Homework Help: Frictionless Pulley Question

1. Oct 13, 2009

### Chandasouk

1. The problem statement, all variables and given/known data

Atwood's Machine. A load of bricks with mass m_1 = 15.0 kg hangs from one end of a rope that passes over a small, frictionless pulley. A counterweight of mass m_2 = 28.0 kg is suspended from the other end of the rope, as shown in the figure. The system is released from rest.

2. Relevant equations

F=ma

I really don't know what to do for this one. So far, I just calculated the weight of each masses.

Mass 1 Weight = -147N (15)(-9.8)

Mass 2 Weight = -274.4N (28)(-9.8)
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Oct 14, 2009

### Staff: Mentor

What's the question you are supposed to answer?

3. Oct 14, 2009

### Chandasouk

Sorry, I have a bad habit of not posting the questions now for some odd reason.

What is the magnitude of the upward acceleration of the load of bricks?
Take the free fall acceleration to be g = 9.80 m/s^2.

What is the tension in the rope while the load is moving?
Take the free fall acceleration to be g = 9.80 m/s^2.

4. Oct 14, 2009

### Staff: Mentor

The upward acceleration of the bricks will be the same as the downward acceleration of the counterweight. Seems to me that the difference between the two weights is important somehow.

For the tension in the rope, I would think the weights add.