A 3200 kg police car traveling North at 40 m/s collides with another car also traveling North. The second car has a mass of 2000 kg and its velocity is 30 m/s North just before the collision. If the cars stick together on contact what will be their common velocity just after collision? Neglect the effect of friction from the road.

Simon is writing a story about an astronaut whose spacecraft has been boarded by space pirates. the astronaut has her lucky penny in her hand behind her back as the space pirates break into the control room. she has just locked the controls so that the ship is accelerating in the direction of the control room’s ceiling. simon wants the astronaut to use the penny to hit a button on the control panel to turn off the lights and escape. the button is located a short distance behind and below the astronaut’s hands. how should simon use the theory of relativity to describe what the astronaut must do in order to hit the button?