Q. An electron and a positron each have a mass of 9.11 x 10-31 kg. They collide and both vanish, with only electromagnetic radiation appearing after the collision. If each particle is moving at a speed of 0.36c relative to the laboratory before the collision, determine the energy of the electromagnetic radiation.
Q. A spring with spring constant 13 N/m hangs from the ceiling. A ball is attached to the spring and allowed to come to rest. It is then pulled down 8.5 cm and released. The ball makes 26 oscillations in 18 s seconds.