Sunday, January 31, 2010

Application: My question...

How can the ideas of circular motion help separate objects of different densities, as in centrifuges?

I will be talking about:
1. How they work
2. What they are
3. Their uses
4. Why they have been misnamed

All of the answers to these questions will be revealed in my upcoming Prezi...

Sunday, January 24, 2010

Application: Should centrifuges really be called centrifuges?

When deciding to choose the topic of centrifuges for application, I was faced with the question, should they really be called centrifuges? As we know, there is no such thing as a centrifugal force because there is no outward force. There is a centripetal force, which points inward, and acts against the natural inertia of the object to keep going in a straight line, hence making the path a circle.
Centrifuges use circular motion to separate different objects, mostly liquids, from one another. The ones of more density go outward while the ones of less density go inward. This manipulates the centripetal force and acceleration, using it in order to keep some things moving in a circular path while others try to break free of it, pushing themselves to the side.
This may be why it seemed obvious to name the centrifuge "the centrifuge," but is it really? What's going on is that the heavier objects are undergoing a centrifugal SENSATION, that naturally pushes them outward along with its inertia. What it is not feeling is the fake centrifugal force. The lighter objects are undergoing a centripetal force that tends to keep them in motion.
In conclusion, I think that centrifuges should be renamed. Perhaps "centripuges" or "centripetages" are more appropriate, but that is not really for me to decide.

Sunday, January 10, 2010

Ref 2: N2L

When being taught about Newton's Second Law, I learned many things. The majority of this is comprised of the acceleration a system experiences when acted upon by an unbalanced force. This is includes the friction that an object experiences when moving (neglecting air resistance, usually). I learned about using my FBDs to calculate the sum of the forces, ∑Fx and ∑Fy, and setting them equal to ma (mass*acceleration). This includes pulley systems and Atwood's machines. I also learned about the coefficient of friction, called mu. This can be obtained from the equation Ff=mu*Fn. Mu is actually a legal naked number because it is obtained by dividing newtons by newtons.
What I have found particularly difficult is solving for the acceleration with very limited information, such as not knowing the mass or weight of the object. I also find it very difficult to find mu in complex situations, such as when the object is accelerating or under certain circumstances and restrictions.
As far as my problem solving skills go, I am satisfied. I feel as though I have mastered FBDs and finding the sum of the forces in one axis. I am good at solving equations for what is needed. I also particularly enjoy the problems relating to Atwood's machines. I am still new to finding mu, which poses difficulties. I also worry when I am given limited information. I always do work to my fullest effort though, so success is soon to follow.