Q. A pair of red lights mounted 1 meter apart are far enough away that they are barely resolvable as two sources. A similar pair of blue lights (also 1 meter apart) is also mounted far enough away as to be barely resolvable. Which pair of sources is farthest from the observer? Justify your answer.
Q. our little sister builds two tree houses and stretches a rope between them for sending messages to the other tree house. She hangs a mass of 1.4kg on one end of the rope that passes over a pulley. The other end is tied to the other tree house. When she plucks the rope, a wave propagates at 18m/s. This is too slow, and she desires to increase the wave speed to 30m/s. She asks you, "What mass should I use?"