Physics 272: Honors Physics II
Spring 2017

# Monday 30 January 2017: Topics to be covered in the lecture (HRW sections 16.1, 16.2 and 16.4)

• Wave motion: wavelength and speed
• Waves on a stretched string
• The wave equation

1. To prepare for the discussion of waves, we need to review the basics of periodic motion and oscillations studied last fall in Chapter 15, especially the concepts of amplitude, period, frequency, angular frequency and phase. Carefully reread the first half of Section 15-1 (up through Checkpoint 1, which you should redo).
Do quizlet questions 1, 2 and 3.

2. Our main system will be waves on a stretched string. To get started, play with the PHET simulation at
First, in the upper left hand corner, choose Oscillate. In the upper right hand corner choose No End. At the bottom, slide Damping to None. Change the amplitude and get a feel for how the motion of the string changes. Next, change the frequency and get a feel for how the motion of the string changes. Turning slow motion on can be helpful.

3. Note how the beads on the string move only up and down in the vertical direction in periodic motion (focus on one of the green beads in the middle of the string). If you change the amplitude, how does the motion of an individual bead change? If you change the frequency, how does the motion of an individual bead change?

4. Let's do one last experiment with the PHET simulation from #2 above: find the time it takes for a crest of the wave to travel the length of the string (you can make a stopwatch appear in the lower right corner of the screen by clicking the Timer box at the bottom). How does this time change if you change the amplitude? How does this time change if you change the frequency? TO GET THE RIGHT ANSWER, YOU HAVE ACTUALLY TO MEASURE THE TIME FOR TWO DIFFERENT VALUES!! Turning slow motion on can be helpful.
Do quizlet question 4.

YOU SHOULD PREVIEW THE QUIZ QUESTIONS HERE TO BE READY TO ENTER THEM WHEN YOU START THE QUIZ IN QUIZSTAR.