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. 

Sunday, January 10, 2010

Newtons Second Law!!

Part A
Q1. This is what i have learned about Newtons Second Law.  I learned the equation: Ef=ma, which is very helpful. I learned that the acceleration of an object is proportional to the net force and inversely proportional to the mass of an object, and the direction of an object is the same as the direction of the acceleration. Newtons Second Law links the cause (force) and the effect (acceleration) in a definite way.

Q2. What i have found difficult about what i have studied is being able to break down the problem and draw a FBD. To me, once you have drawn a FBD correctly, it is very easy to solve a problem. But sometimes i have trouble drawing a correct FBD because there are so many parts to a problem and i get overwhelmed. I hope I can learn to draw more correct FBD'S.

Q3. My problem solving skills are weaker than they should be. Lately i have been doing better in my problem solving skills. A couple of weeks ago, i would see a difficult problem and just not even try it. I would just look at it. Lately i have been able to get through many problems by breaking them step by step. I find the tactic very easy and helpful. My strengths are the algebraic parts of the problems. Once the FBD is drown and i can gather all of the data, I am good at setting up the equation for the sum force and solving for the unknown variable.

Part B.
Q1. There are many ways you can use what we have learned in Newton's Second Law in real life situation. Sort of like the problem on our last test, if you needed to find out a certain tension to lift an object off of the ground, we know to find the tension now! If you needed to move something, we now can figure out to amount of force you would need to exert on the object. I hope I will be able to use what we learned in class during real life experiences!