1. A 3.1 kg cart is traveling at 7.12 m/s to the right and it has a head on elastic collision with a 11.7 kg cart traveling at 1.12 m/s to the left. If the final velocity of the first cart is 1.263 m/s to the left, what is the final velocity of the second cart?

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?

What is the force that opposes motion and works against the downward pull? a) friction b) gravity c) weight d) acceleration

Contrast the force of gravity between these pairs of objects: 1-kg mass and a 2-kg mass that are 1 m apart; a 1-kg mass and a 2-kg mass that are 2 m apart; and two 2=kg masses that are 1 m apart. i dont understand.