Class: October 30, 2009

Today in class, we started off by breaking off into groups to write equations that expressed how to find centripetal acceleration or the factors that affect it. On the board, there was a triangle that represented an angle (theta), the hyptonuse (length of the rope the object was attached to), and the side opposite theta (the radius of a circle). There was also a free body diagram of Ft pointing northwest, a dotted line going straight up, an angle between those two lines represented by the same theta, and gravitational force pointing straight down.

The first question we had to answer was which way the net force would point: a little less than horizontally in the west direction.

Question 2 asked to draw a diagram of all of the forces acting on the object expressed in the free body diagram. Unfortunately, I do not know how to put my picture of it on the post so I cannot show it.

The next question was to find an expression for R by using the triangle. We knew that the sin of theta was equal to the R/L, so we also knew that R was equal to sin of theta multiplied by L.

Question 4 was to find an expression for the Fnet by using theta and Ft. We knew that sin theta would be equal to Fnet/ Ft if we looked at the free body diagram, so we also knew that sin theta multiplied by Ft was equal to Fnet.

Question 5: Write an expression for Fnet in terms of m and ac. We knew that f=ma, so we also knew that Fnet=mxac. We also knew that ac=4 times pi squared/ t squared, so Fnet=m times ((4 times pi squared)/t squared))

Question 6: Use the expressions from 3, 4, and 5 to make an xpression for Ft. Ft= Fnet/sin theta. Using the previous equations, we knew Ft=(m(4 times pi squared times R/time squared)/(R/L). Simplified, Ft=(m(4 times pi squared/time squared)/L.

After that we went and saw the halloween parade, came back, and did the lab. Our homework is to plot a force vs. acceleration graph of our results.

This is the 100th scribe post. The next scribe is Jason. Happy Halloween.