A 60 watt bulb illuminates a surface distance d away with a illuminace of 1800 lux. what would be the illumanice on a surface distance 0.5.d away (ie. one-half the distance away) when illuminated by a 120 watt bulb

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.