Q1. A rifle that shoots bullets at 420 m/s is to be aimed at a target 49.0 m away. If the center of the target is level with the rifle, how high above the target should the rifle barrel be pointed so that the bullet hits dead center?
Q2. Coherent light with wavelength 600 nm passes through two very narrow slits and the interference pattern is observed on a screen 5.00 m from the slits. The first-order bright fringe is at 4.74 mm from the center of the central bright fringe. For what wavelength of light would the first-order dark fringe be observed at this same point on the screen?