Atwood Machine Lab: Solving Force Equations w/ Friction

[BlueMedic]

First of all, I'd just like to apologize for me asking for help in my first post. I know that seems kind of lame.

Homework Statement

The lab involves an Atwood's machine which is basically two masses attached to some kind of pulley system so that if the masses are equal, the system will be in equilibrium. There's a much better explanation on Wikipedia. Our system has two small pulleys at either end.

I'm supposed to come up with the force equations for determining the value of g, but I can't seem to figure out how to factor in friction.

Homework Equations

Net Force = ma

The Attempt at a Solution

I drew the free body diagrams for both masses and did all the equations and whatnot to come up with:
[tex]g=\frac{2d(m_{1}+m_{2})}{t^{2}(m_{2}-m_{1})}[/tex]

Then I realized that I never took friction into account. I was absent for the first day of this lab so I missed most of the data collecting, and all I have written down for friction is that it took .026kg difference in the masses to overcome the frictional force. I'm pretty sure were not supposed to take rotational inertia or something into account since we haven't learned that yet. Any assistance is much appreciated.

 

[anathema]

First of all, don't apologize for asking for help. Asking for help is a sign of intelligence and a willingness to learn, which are important qualities for a scientist.

Now, onto your question about factoring in friction in your Atwood's machine experiment. Friction is an important factor to consider in any experiment, as it can greatly affect the accuracy of your results.

To incorporate friction into your force equations, you will need to add an additional force term to the equation. This force is known as the frictional force, and it is equal to the coefficient of friction (μ) multiplied by the normal force (N) exerted on the object. The normal force is the force exerted by the surface on the object, and it is equal to the weight of the object in this case.

So, your new force equation would look like this:

Net Force = ma + μN

To determine the value of μ, you will need to use the information you have about the difference in masses needed to overcome the frictional force. This can be used to calculate the normal force and then the coefficient of friction.

Also, make sure to take into account the direction of the frictional force. It will act in the opposite direction of the motion of the masses, so it will have a negative sign in your equation.

I hope this helps you in your experiment. Remember, asking for help is always a good thing, and it shows that you are dedicated to finding the right answer. Best of luck with your experiment!

 

[thomate1]

Hello,

No need to apologize for asking for help, it's important to seek assistance when needed in order to fully understand the material.

In this lab, you are correct in your understanding that the Atwood's machine is a system of two masses connected by a pulley. In order to solve for the force equations, you will need to take into account the forces acting on each mass, including the force of friction.

To account for friction, you will need to add the force of friction to the net force equation. The force of friction can be calculated using the coefficient of friction and the normal force (which is equal to the weight of the mass). The coefficient of friction can be determined experimentally by measuring the difference in mass needed to overcome the frictional force, as you have done.

It is also important to note that the force equations you have written may not be accurate if the masses are not equal or if the system is not in equilibrium. It may be helpful to review the concepts of equilibrium and Newton's laws of motion to better understand the force equations you have written.

I hope this helps and good luck with your lab!