set1-soln - Physics 1240 Homework 1 solutions Brief...

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Physics 1240 Homework 1 solutions Brief solutions to homework set #1. Your numbers will be different, but the idea is the same. I’m just using sample numbers here. 1. The graph below represents the function Y = ax . Make a graphical estimate of the value of a . Here the key idea is that the slope a , is the change in Y divided by the change in x (the “rise” over the “run”). Reading off the graph, for this example Y increased from 0 to about 11 when x changed from 0 to 2, giving a slope a 5 . 5. 2. Because Boulder is above sea level, normal atmospheric pressure is not 1 atm. Suppose the atmospheric pressure is 0.850 atm on a given day. If the rarefactions of a particular sound wave then reduce the pressure to 0.846 atm, what is the amplitude of the pressure wave? Is this a loud sound or a soft sound? How do you decide? The underpressure is 0.850 - 0.846 atm = 0.004 atm, which is the same as the amplitude of the pressure wave. To convert this to Pa, use the conversion that 1 atm = 1 . 013 × 10 5 Pa, so we have 0 . 004 atm × 1 . 013 × 10 5 Pa 1 atm = 405 . 2 Pa . In class and in the reading, we discussed an example of a sound with an amplitude of 1 Pa, and explained that this pressure corresponds to a loud but normal sound. Your ear is a very sensitive detector, capable of hearing pressure variations of only 1 part in 10
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set1-soln - Physics 1240 Homework 1 solutions Brief...

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