A roller coaster car of mass 90 kg has two people seated in it whose combined mass is 130 kg. If the height of point A from the ground is 80.0 m, determine the potential energy of the car with the people in it at A. 172 kJ
70.6 kJ
17.6 kJ
86.2 kJ

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