Class notes 28

course phy 121

I'm stuck. I understand the theory behind rotational motion, but I can't get the math to work out. In class notes 28 under the heading

Analysis of Actual Data

Please explain how theta and radians of the two angles was calculated. I don't get the same answers at all.

Inverse tan ( 3.2/8) is angle 1. I calculate the angle to be 22 degrees. Then change to radians by multiplying 22degrees by pi rad / 180 degrees. I round down to 20 degrees and get pi/90 rad. If I calculate that out further I get .03 rad, which isn't anywhere close to the .38 rad that you have. Please explain so I can move along.

In the first place a radian is a little less than 60 deg, so 20 deg would be a little more than a third of a radian. So 22 deg = .38 rad is very plausible (.03 radians isn't).

The details of the calculation:

22 deg * (pi rad / 180 deg) = 22 pi rad / 180 = (22 pi / 180) rad. Ballpark that's about 70/180, which is close to .38.