1. A kg canoe moving to the left at 12.5 m/s makes an elastic head on collision with a raft moving to the right at 16.0 m/s . After the collision the raft moves to the left at - 14.4 m/s . Assuming water simulates a frictionless surface, what is the velocity of the canoe after the collision?

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.