Sound with a frequency of 1250 hz leaves a room through a doorway with a width of 1.05 m. at what minimum angle relative to the centerline perpendicular to the doorway will someone outside the room hear no sound? use 344 m/s for the speed of sound in air and assume that the source and listener are both far enough from the doorway for fraunhofer diffraction to apply. you can ignore effects of reflections. theta = ? degrees, ? degrees, ? degrees (should be three terms)

An observer that stands still as the electron moves by him, will observe

Part f - example: finding two forces (part i) two dimensional dynamics often involves solving for two unknown quantities in two separate equations describing the total force. the block in (figure 1) has a mass m=10kg and is being pulled by a force f on a table with coefficient of static friction îľs=0.3. four forces act on it: the applied force f (directed î¸=30â above the horizontal). the force of gravity fg=mg (directly down, where g=9.8m/s2). the normal force n (directly up). the force of static friction fs (directly left, opposing any potential motion). if we want to find the size of the force necessary to just barely overcome static friction (in which case fs=îľsn), we use the condition that the sum of the forces in both directions must be 0. using some basic trigonometry, we can write this condition out for the forces in both the horizontal and vertical directions, respectively, as: fcosî¸â’îľsn=0 fsinî¸+nâ’mg=0 in order to find the magnitude of force f, we have to solve a system of two equations with both f and the normal force n unknown. use the methods we have learned to find an expression for f in terms of m, g, î¸, and îľs (no n).

Why is it important always to use horizontal bars in unit fractions when performing unit conversions?