(ii) a very thin sheet of plastic (n = 1.60) covers one slit of a double-slit apparatus illuminated by 680-nm light. the center point on the screen, instead of being a maximum, is dark. what is the (minimum) thickness of the plastic?

Abatter hits a 0.140-kg baseball that was approaching him at 30 m/s and, as a result, the ball leaves the bat at 40 m/s in the reverse of its original direction. the ball remains in contact with the bat for 2.0 ms. what is the magnitude of the average force exerted by the bat on the ball?