Q1. A 23 g ball is fired horizontally with initial speed toward a 110 g ball that is hanging motionless from a 1.1m long string. The balls undergo a head on, perfectly elastic collision, after which the 110 g ball swings out to a maximum angle theta max= 51. What was v0?
Q2. A spaceship moves past you at speed v. You measure the ship to be 285m long, whereas an astronaut on ship measures a length of 380m. Find out v.