Wednesday, January 27, 2010

Circular Motion and Gravitation

A. This is what I learned about circular motion and gravitation. Uniform circular motion is the motion of an object in a circle with a constant or uniform speed. The speed going around a circle is defined as v= 2πR/T. The period (T), is the time to complete one full rotation or revolution and is given in seconds. The frequency is the number of rotation per unit time, this unit is called Hertz (Hz). If the object is changing directions, it is accelerating. In the circular motion, it is called centripetal acceleration. Centripetal means it is always pointed toward the center. The formula for centripetal acceleration is Ac= V^2/R (m/s^2). The inward force that keeps the object moving in a circle is called centripetal force. The equation for this is Fc= mv^2/r.  When attached to a string, the highest point of the vertical circular turn is given by Ft + Fg= mv^2/r, while the lowest part is Ft - Fg= mv^2/r. The law of universal gravitation states that " Every object in the universe attracts every other object in the universe with a force that varies directly with the product of their masses and inversely with the square of the distance between the centers of the two masses." To find the force of gravitation, use the equation Fg= Gm1m2/r^2.  To find the acceleration due to gravity (g), use the equation g=GM/r^2.

B. What I have found difficult about what I have studied is the Universal Gravitation. To me, the circular motion is pretty easy,  but the Universal Gravitation is difficult. I have trouble with scientific notation in the problems, and i get confused what to substitute into the different equations. Usually there are a lot of masses and i don't know which to substitute in. I also have a little trouble the "mu", and seeing that i can substitute Fn for mg when Fn=Fg. 

C. My problem solving skill are strong in the circular motion problems, but in the Universal Gravitational problems, i have had a little trouble. The scientific notation, is frustrating, and sometimes messes me up with all of the number. It is also very easy to mess up on your calculator. I have also trouble knowing what to substitute into the equations. I am also very confused with all of the big G's, small G's, big M's, and small M's. 

1 comment:

  1. Your description of Vertical Circular motion implies that tension always involved, is that correct? how about when traveling around a loop in a roller coaster? how about a ferris wheel? or even simpler, how about a car going over a hill?
    Please explain this part.