A10.0 kg block on a table is connected by a string to a 63 kg mass, which is hanging over the edge of the table. assuming that frictional forces may be neglected, what is the magnitude of acceleration of the block when the other block is released?

Light traveling in water, nwater = 1.33, strikes a plastic block at an angle of incidence of 51.4°; part of the beam is reflected and part is refracted. if the index of refraction of the plastic is 2.0, what is the angle made by the reflected and refracted beams?