A 1000 kg weather rocket is launched straight up. the rocket motor provides a constant acceleration for 16 s, then the motor stops. the rocket altitude 20 s after launch is 5100 m. you can ignore any effects of air resistance. a. what was the rocket's acceleration during the first 16 s?
b. what is the rocket's speed as it passes through a cloud 5100 m above the ground?

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina.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 2.05cm in front of the eye.)