1. The problem statement, all variables and given/known data http://paer.rutgers.edu/PT3/experiment.php?topicid=5&exptid=61 You can use the arrow keys to watch frame by frame (later used to measure time) 2. Relevant equations F_friction = [tex]\mu[/tex](f_normal) F_c = mv^2/r 3. The attempt at a solution So in the first attempt radius is 7 inches. We can find time by counting the number of frames it takes the coin to make 1 revolution (by using the arrow keys), and then dividing by 15 (since it's at 15 frames per second). Dividing the circumference by time would give us velocity. From here I wasn't sure where to go, so using the second half of the video I drew an incline. We were given the right side of the incline , 10 in., and the hypotenuse, 15 in., so I calculated theta, 41.81 degrees. Then I knew the force parallel to the incline was mgsin(theta), and Fnormal was mgcos(theta). Again, I wasn't sure from here after but here is how I solved for mu: From the point where it stood and then fell was 9 inches (estimation), and the time it took was .4 seconds (6/15). Since velocity is displacement/time, I plugged in and got .05715 m/s. Then i did v/t to solve for acceleration and got a value of .142875 m/s^2. I set up another equation, where [tex]\sum[/tex]F = (F_parallel - F_friction) + (F_grav - F_normal) I reduced this to [tex]\mu[/tex] = ((a/g) + cos(theta) - 1 - sin(theta))/(-cos(theta)) Plugging in gave me [tex]\mu[/tex] = 1.255 We did this in class, but I forgot exactly how we solved for mu. A friend of mine got .3 as an answer. Can someone please explain the appropriate method, or guide me toward it.