Physics 202 homework question

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

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?

Takumi works in his yard for 45 minutes each saturday. he works in the morning, and he wears sunscreen and a hat each time he works in the yard. what does takumi hope to reduce through his actions? the likelihood of stochastic effects, such as dna mutations the severity of stochastic effects, such as cancer the severity of non-stochastic effects, such as cancer the likelihood of non-stochastic effects, such as radiation sickness