Standing waves from spring semester

Take a look at the standing wave demonstration from last spring, Gloria and Lee operating the Slinky.
You can read more about standing waves and harmonics on pp. 129-130 of our present textbook.

Here is another YouTube, with Amanda and Rylee. They actually get up to the 2nd excited state. Nice.

Only Gloria!

Only Miss Gloria can do this.

WOW!

Here are some other links to slightly less spectacular demonstrations of the Van de Graaff generator:

1. Hair troubles
2. Lydia, Michelle and Madeleine
3. Lydia's hair demonstration

Nice

From a few semesters ago, atmospheric pressure crushing power.



Nice.

Angular momentum videos

You now can view the angular momentum demonstrations from Thursday lecture, in iTunes U and in YouTube.



Also available are the last two pendulum videos, as promised.





I will be asking questions about all of these demonstrations on Exam 2.

Pendula and oscillation period

I will be posting several videos from the long pendulum demonstration on Thursday, Feb. 17. Here is the first one, from the beginning of the demonstration.



This video is also available inside our iTunes U area.

Demonstrations tomorrow: pendulum and quantum physics

Tomorrow (Thursday) we will have a demonstration and measurements of the periodic behavior of pendula. Amanda and Rylee will be taking digital video, too, for iTunes U and YouTube.

We will also map out the momentum of the pendulum and build a foundation for the quantum physics on our agenda for the last three weeks of the semester.

Erin's reaction time

You guys in the after lunch bunch, Sec. 0002, we forgot to calculate Erin's average reaction time! Oh, no!

Here are the drop distances:

1. 30 cm
2. 20 cm
3. 21 cm
4. 8 cm

And the average drop distance is (79 cm)/4 which is 19.75 cm.

Now: we know what the general formula for drop distance is, connecting drop distance with drop time, second by second.


So for Erin, her average drop distance equals one half g times the square of her reaction time:


Better convert those centimeters to meters.


Now: divide both sides by 4.9, and you get t_reac² = 0.0403 sec². Hit the square root key on your calculator, and you get Erin's reaction time, t_reac = 0.20076 sec, very similar to Kendall's reaction time from the morning section 0001.

Nice work, Erin and Kendall.