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For more information, please see full course syllabus of AP Physics 1 & 2
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Lecture Comments (2)

1 answer

Last reply by: Professor Dan Fullerton
Sun Dec 6, 2015 6:31 PM

Post by imane abbadi on December 6, 2015

I am looking for waves lectures and i can't seem to find them in order .  please help

Wave Behaviors

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Question 1 0:13
  • Question 2 0:40
  • Question 3 1:04
  • Question 4 1:17
  • Question 5 1:39
  • Question 6 2:07
  • Question 7 2:41
  • Question 8 3:09

Transcription: Wave Behaviors

Hi everyone and welcome back to 0000

In this mini-lesson, we are going to do page 1 of the APlusPhysics worksheet on wave behaviors. 0003

You can find the link to this worksheet down below the video. 0007

Let us dive right in. 0011

Number 1 -- While playing, two children create a standing wave in a rope as shown in the diagram below. 0013

A third child participates by jumping the rope. 0018

What is the wavelength of this standing wave? 0021

Well, it looks like that is showing half a wavelength because if I were to continue that wave, we would have to go back to there, for a total of 8.6 meters, so the wavelength of that wave must be 8.6 m. 0023

The correct answer is Number 4. 0037

Number 2 -- The diagram below shows two pulses approaching each other in a uniformed medium -- 5 cm to the right and 10 cm moving to the left. 0041

Which diagram shows their super position? 0056

Well, that just means we are going to add them up. 0058

The correct answer there must be Number 2. 0060

Number 3 -- Sound waves strike a glass and cause it to shatter. How sad. 0065

This phenomenon illustrates -- well that is resonance, Number 1. 0069

Number 4 -- A sound of constant frequency is produced by the siren on top of a firehouse. 0077

Compared to the frequency produced by the siren, the frequency observed by a firefighter approaching the firehouse -- so if the firefighter is coming closer to it, the Doppler Effect says, they are going to observe a higher frequency. 0083

The correct answer there must be Number 2. 0095

Number 5 -- The super position of two waves traveling in the same medium produces a standing wave pattern if the two waves have -- well if the two waves have the same frequency, the same amplitude and travel in the same direction, they are not going to interfere. 0100

If they have the same frequency, the same amplitude and travel in opposite directions, you are going to get a standing wave. 0114

There is the right answer. Correct answer to Number 5 is Number 2. 0119

Number 6 -- The diagram below represents a standing wave. 0127

The number of nodes and anti-nodes shown in the diagram is...?0130

Well let us count the nodes. 0133

Nodes are the points that vibrate with minimum amplitudes, so we have 1, 2, 3, 4, 5, 6 nodes and then we have our anti-nodes, 1, 2, 3, 4, 5 and there is always one less anti-node than node. 0135

So we have 6 nodes, 5 anti-nodes and the correct answer there must be Number 3. 0155

Number 7 -- A car's horn is producing a sound wave having a constant frequency of 350 Hz. 0162

If the car moves toward a stationary observer, at constant speed, the frequency of the car's horn detected by this observer may be... 0168

Well the Doppler Effect says if they are going towards each other, they are going to observe a higher frequency. 0176

The only answer here that is higher than 350 Hz is Number 4, 380 Hz. 0181

All right, one more. 0188

Standing waves and water are produced more often by periodic water waves being absorbed at the boundary with the new medium. 0190

Well, that is not going to do it -- refracting at a boundary with a new medium -- No...0198

...Diffracting around a barrier -- now that is bending around the barrier, but that is not going to give you standing waves...0203

...Reflecting from a barrier -- Yes -- that way you get the same amplitude, same frequency traveling in an opposite direction. 0208

So the correct answer to Number 8 is Number 4. 0215

Hopefully, this went well as we finished up the page on wave behaviors, but if it did not go so well, now would be a great time to go review it and if it did go well, well, keep moving on to the higher level questions. 0219

Thanks everyone for your time and make it a great day!0230