Conservation of Mechanical Energy Lab

For this lab, you obviously should compare the change in PE, from the point where the cylinder is released to the bottom of tis arc, with the gain in KE from the release point to the bottom. Since KE = 0 at the release point, the change in KE is simply the KE at the bottom. Therefore you should be finding out if Mg (hrelease- h bottom) = Mv(at bottom)squared/2.

We find v from diameter/t because the light is blocked for the time it takes the cylinder to travel one diameter as it passes through the photo gate. However, this is not quite accurate. The light is not completely blocked until the cylinder reaches the far edge of the bulb in the photogate head, and light starts to leak through once the back edge of the cylinder passes the near edge of the bulb. So in effect, the cylinder only has to travel its diameter - the bulb diameter, during the time the light is blocked. Even this is not quite right since the hole the light enters is much smaller than the bulb, so maybe the correct distance is cylinder diameter- hole diameter or something between the two. Think about it and you might use it to explain why your first calculation of KE may be greater than the initial PE.