Free body diagram of atwood machine

In summary, the modified Atwood machine in the provided image has three forces acting on the mass above the spring: T, -mg, and -kx. The mass below the spring also experiences three forces: -mg, kx, and -T. The mass M only experiences two forces: Mg and -T. The spring force also plays a role in determining the forces on the masses.
  • #1
Shukie
95
0

Homework Statement



I need to find the forces on this modified atwood machine:

http://imageshack.us/photo/my-images/36/atwood.jpg/

The Attempt at a Solution



What I think:

- On mass M there are two forces, Mg and -T.
- On the mass above the spring there are two more forces, -2mg and T.
- On the mass below the spring there are also two forces, -mg and kx.

Is any of this correct?
 
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  • #2
You seem to have got it right.
 
  • #3
Thanks.
 
  • #4
Shukie said:
- On the mass above the spring there are two more forces, -2mg and T.
Careful: The only force of gravity on that mass is mg. (But there's a spring force on it.) So there are three forces acting on that mass.
 
  • #5
Doc Al said:
Careful: The only force of gravity on that mass is mg. (But there's a spring force on it.) So there are three forces acting on that mass.

Ooh, you're right, I was thinking there might be a 2mg plus a kx after you mentioned the spring force, but I think it's only mg and kx.

I knew the spring was going to make it trickier than I had thought.
 
  • #6
Are the forces on the mass above the spring then T and -mg and - kx?
 
  • #7
Shukie said:
Are the forces on the mass above the spring then T and -mg and - kx?
Yes.
 
  • #8
Thanks
 

1. What is a free body diagram?

A free body diagram is a graphical representation of all the forces acting on an object. It is used to analyze the motion of an object and determine the net force acting on it.

2. What is an Atwood machine?

An Atwood machine is a simple machine consisting of two masses connected by a string or rope that passes over a pulley. It is used to demonstrate principles of force, acceleration, and motion.

3. What are the forces acting on an Atwood machine?

The forces acting on an Atwood machine are the tension in the string, the weight of each mass, and the force of gravity.

4. How do you draw a free body diagram of an Atwood machine?

To draw a free body diagram of an Atwood machine, first identify the two masses and the string connecting them. Then, draw arrows to represent the direction and magnitude of each force acting on each mass, including tension, weight, and gravity. Label each force accordingly.

5. How does the mass difference affect the motion of an Atwood machine?

The mass difference between the two masses in an Atwood machine affects the acceleration of the system. The greater the mass difference, the greater the acceleration. This is because the net force on the system is equal to the difference in weight between the two masses.

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