The Wave Dynamics of a Spring A.K.A. The Crests and Troughs of a Physics Teacher Using New Equipment Molly Thomas Chatham Hall April 5, 2001

Tips on Using a Motion Detector for Simple Harmonic Motion Attach a index card or cardboard to your mass Attach the motion detector to the vibrating mass- allow floor to be the target Use a light-weight notebook as a pendulum

After following these tips I expected wonderful smooth data…

I got junk.

I tried different techniques Making sure the spring was in motion before I started data collection Securing the spring support Checking the surrounding area Mounting the motion detector on the mass Nothing worked until…

I changed the sampling rate (It’s found under the Experiment tab in LoggerPro) Beautiful Data !

This discovery about sampling rate became one of my primary goals of the Spring Lab

Purpose: To determine how sampling affects the motion data To observe how velocity and acceleration change as motion changes To determine the amplitude, frequency, and the Period of a mechanical wave

Apparatus Support Rod Clamp spring 1kg mass flat cardboard Tape LoggerPro LabPro Vernier Motion Detector

Program Start LoggerPro Open File Experiments Probes & Sensors Motion Detector

Data Collection Students worked in groups of 3-5. They traded assignments for each trial.

Sampling Comparison The 3 graphs were at different sampling rates (20, 40, 50 samples/s) There was no observable effect of the sampling on the motion data.

Motion Comparison This analysis was obtained by comparing the distance, velocity, and acceleration waves. The examine button key in LoggerPro allows this to be done easily.

Wave Characteristics Amplitude= (Position of Crest – Position of Trough = (.556m-.514m)/2 =.021 m Frequency = number of complete oscillations / s = 5/(4.646s-1.049s) = Hz Period= reciprocal of the frequency =1/1.309 Hz =.7194 s

Student Assessment The groups saved their data in LoggerPro and in a word document I ed data and pictures to each student The student created an electronic lab report which they ed back to me.

Why did the sampling rate affect the data one day but not another ?

The motion detector is sensitive to humidity

Thanks To my wonderful Physics Students To my Chatham Hall Colleagues – June Tuttle, Maureen Miller, & David Lyle To Kim Clifton, Randy Cromwell, and the Pittsylvania County Teachers