1.when is the mechanical energy stable? 2.a moving body exerts a constant force in the direction of its velocity. is the work of this force constant? Yes or no and why?

sorry if there's any mistake in englisht because english is not my first language :D

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

Abar magnet cut in half will form a total ofpoles.a)fourb)eightc)two

What component of earth’s atmosphere exists entirely as a result of photosynthesis?