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AP Physics B: Waves and Optics Drill 1, Problem 1. Which of the following is technically true for Max as he stands still at the edge of oblivion?
AP Physics 2: 1.1 Properties of Objects and Systems. What is the magnitude and direction of the conventional current in this wire?
AP Physics B 1.1 Waves and Optics 185 Views
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Description:
AP Physics B: Waves and Optics Drill 1, Problem 1. Which of the following is technically true for Max as he stands still at the edge of oblivion?
Transcript
- 00:03
Here's your shmoop du jour, brought to you by the Grand Canyon.
- 00:07
Almost as awe-inspiring as AP Physics.
- 00:10
Max is scolded by his parents for leaning over the railing of a dangerous vista at the Grand Canyon.
- 00:15
Mom conveys her distress as she steps back from the ledge,
- 00:18
and Dad cries out while lunging forward to grab his son.
Full Transcript
- 00:21
Which of the following is technically true for Max
- 00:23
as he stands still at the edge of oblivion?
- 00:26
You know... other than the fact that he now has proof his parents love him?
- 00:30
And here are the potential answers...
- 00:36
This problem doesn't have a lot of numbers, so it's clearly a conceptual one.
- 00:39
Heck, there are no numbers at all. If we glance at the answers,
- 00:42
we'll see that they all have to do with the perceived pitch of Max's parents' cries.
- 00:47
Also, the problem give us information on the motion of his parents.
- 00:51
When we have waves and movement, our mind should immediately snap to the Doppler effect.
- 01:01
Named for Christian Doppler, it's the phenomenon that occurs when a source of waves is in motion.
- 01:06
Say, for example, that we had a speaker emitting a tone with a frequency of 100hertz.
- 01:12
A listener 1 meter away would hear a frequency of 100 hertz.
- 01:16
A listener 2 meters away would hear the same frequency.
- 01:20
No matter how far, the sound is still 100 hertz.
- 01:23
But, uh... what the heck is a hertz?
- 01:26
A hertz is a measurement of one cycle of sound per second.
- 01:30
One hertz every second the sound wave oscillates - moves up and down - one time.
- 01:36
If a sound has a frequency of 100 hertz, it oscillates 100 times in a second.
- 01:44
This rate of oscillation determines how high or low a sound is.
- 01:47
A higher frequency means a higher sound.
- 01:50
What if the speaker starts moving?
- 01:52
If the speaker moves away from the listeners, then the distance between each wave would increase.
- 02:02
This decreases the frequency and creates a lower tone.
- 02:06
On the other hand, if the speaker moves toward the listeners,
- 02:09
the waves would become closer together, and a higher tone would be heard.
- 02:17
So Max's father moving toward him will sound higher, and his mother will sound lower.
- 02:22
The only answer that fits this description is (D).
- 02:26
Next year's family vacation?
- 02:28
Kansas.
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