Aformer student of mechanics wishes to weigh himself but has access only to a scale a with capacity limited to 120 lbs and a small 20-lb spring dynamometer
b. with the rig shown he discovers that when he exerts a pull on the rope so that b registers 17 lb, the scale a reads 94 lb. what is his correct weight?

The momentum of an isolated system is conserved a) only in inelastic collisions. b) only in elastic collisions. c) in both elastic and inelastic collisions

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.)

Which of the following situations would produce an average velocity of zero? o a. a horse galloping in a field b. a round-trip to school and back o c. a trip, first to the moon, then onto mars o d. the criss-crossing path of a flying bug