Asnowmobile is used to pull one sled across the ice. the mass of snowmobile and the rider is 315 kg . the mass of the sled is 150 kg. the coefficient of kinetic friction for the sled on ice is 0.15 and the coefficient of kinetic friction on the snowmobile is 0.25. the acceleration of the snowmobile and the sled is 1.9m/^2.
a. what is the net force acting on the system?
b. what is the tension in the rope between the sled and the snowmobile?
c. what is the applied force on the snowmobile?

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.)