Analyzing to Find Flash Delay

Again, we used Adobe Photoshop to measure the angle swept out by the hand in the time between the two flashes. Knowing the period of 1 rotation of the disk (by measuring the frequency using a stroboscope and the formula p = 1/f), we were able to find the amount of time between flashes, since the ratio of the angle swept to the number of degrees in a circle is equal to the ratio of amount of time between flashes to the period of the disk.
This told us the amount of time it took the pendulum to swing through the angle it did in our other picture.