A constant force of 20 N is exerted for 10 s on a 40 kg object initially at rest. The change in
speed of this object will be:

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?