A puck of mass m 5 50.0 g is attached to a taut cord passing through a small hole in a frictionless, horizontal surface (Fig. P11.52). The puck is initially orbiting with speed vi 5 1.50 m/s in a circle of radius ri 5 0.300 m. The cord is then slowly pulled from below, decreasing the radius of the circle to r 5 0.100 m. (a) What is the pucks speed at the smaller radius? (b) Find the tension in the cord at the smaller radius. (c) How much work is done by the hand in pulling the cord so that the radius of the pucks motion changes from 0.300 m to 0.100 m?
Let there be light! 1 History: Maxwell thought that vacuum is a medium Hence strange notations (permittivitpermeability of free space ε0and µ0 1 µ = 0 0 c2 Prediction: speed of light should vary depending on our velocity with respect to aether vapparent = V train − V man/train 2 Michelson-Morley experiment The most famous failed experiment Motion through aether 3 Michelson-Morley