Ablock is attached to the end of a horizontal ideal spring and rests on a frictionless surface. the other end of the spring is attached to a wall. the block is pulled away from the spring’s unstrained position by a distance x0 = 0.050 m and released from rest. the period of the subsequent periodic motion of the block is 0.64 s. at what distance from the unstrained position is the speed of the block equal to 0.30 m/s?

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