Waves

The morning RipStik wave generating run was done this term on the front sidewalk. Conditions were just dry enough. The run had a number of small rocks that had to be cleared first. 

Lacking markers, I chose to use the crayons from lab eight. 

I colored both wheel tracks as I was not sure which I would use. The cement is smoother here than the sidewalk in Pohnpei, the RipStik wave was not quite as clear. 

The paper was laid on the floor - there are no tables long enough to accommodate the 250 cm triple sheet run. 

The wavelength was around 70 cm. There were four crests and troughs visible, but the ends of those four waves were clipped. A calculation of 250 ÷70 suggest 3.6 waves were visible on the paper. Amplitude was 5 to 6 centimeters near the middle of the sheets. 

The time to cross was 1.86 seconds generating a period of about 0.52 seconds and frequency of 1.94 Hertz. A wave speed of 135 cm/s concurs with 250 cm ÷ 1.86 seconds = 134 cm/s. 

The speed of sound is tougher to measure on this campus: the longest distance is 255 meters. I forgot to bring a flagging towel. The clapper was up at the bridge.

The hot pad glove was the flagging device, the flagger noted that they could not see it.

Behind the clapper was the state capitol. 

This is out at 255 meters in the swamp grass. Out here the ground is sodden, I had to walk around an soggy place.

The view back to the clapper at 255 meters. In reality he is far more visible than the photo would suggest. 

Jeffan and class visitor. 

The sparse data was brought back to the classroom for analysis, with rain falling just after the class returned to the lab room. The data was somewhat surprising in terms of accuracy, a speed of 340 m/s was indicated by the data.