Pivot Putty
A piece of putty of mass m = 0.70 kg and velocity v = 2.5 m/s moves on a horizontal frictionless surface. It collides by and sticks to a rod of length L = 0.98 m and mass M = 2.0 kg which pivots about a fixed vertical axis at the opposite end of the rod as shown. What fraction of the initial kinetic energy of the putty is lost in this collision?