A green puck with mass 10 kg strikes a stationary yellow puck with mass 10 kg. The green puck was moving at a velocity of 7i – 6j m/s, and its center was at (1, 2) when it hit the yellow puck. Which of the following could be the velocities of the pucks after the collision? (Assume the collision is elastic.)

With the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 1.90