Pre Lab: Doppler effect and Waves on a String
This week we will be doing 2 labs on waves. One on the Doppler effect and the second on standing waves generated on a string. The second lab (but the first I will write about) explores standing waves, specifically waves on a string. When something happens, it takes time for the effects of that something to reach distant points. For example, when I throw a stone into a pond, it moves the water. The water near the stone moves right away, but the water far from the stone doesn't move immediately. The signal (energy) from the stone moves outward from the initial point as a wave. Waves are made up of peaks (crests) and low points (troughs). They are described by how far the peaks and throughs are from the rest position (amplitude), how fast they are moving (velocity), how many waves there are per second (frequency), and the distance between crests (wavelength).
These factors are related mathematically as we will explore in lab. The videos to the right describe the relationships as well. There are also different types of waves, which we will discuss in class. That being said, waves always transfer energy.
The Doppler Effect refers to a change in frequency due to the movement of the source of a wave. It has applications that range from tracking the movements of weather patterns to tracking the movements of stars and galaxies. Notice in the picture below that the waves are compressed in the direction of the movement of the source. For sound waves we perceive this change as a change in sound as the source passes us (think of a race car passing you on the track or the train in the bottom video on the right). If we can analyze how the frequency changes, we can calculate how the source is moving (Doppler radar for weather, red/blue shifts in astronomy).
In the lab this week we will explore the Doppler Effect through analysis via a computer simulation and use Capstone to generate and explore factors effecting waves on a string. Prior to lab please complete the following:
|
|
Pre Lab Videos
Doppler Effect
Waves on a String
Simulation
Use the simulations embedded at the following links to explore Waves and the Doppler Effect.
Simulation 1: http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600::/sites/dl/free/0072482621/78778/Doppler_Nav.swf::Doppler%20Shift%20Interactive
Simulation 2: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html
You may use the simulations to answer the pre lab quiz questions as well.
More info about the Doppler Effect is available at the following site: http://www.animations.physics.unsw.edu.au/jw/doppler.htm
For more info on Standing Waves check out this link: hyperphysics.phy-astr.gsu.edu/hbase/Waves/string.html
Pre-Lab Quiz is available at the course Blackboard website
Simulation 1: http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600::/sites/dl/free/0072482621/78778/Doppler_Nav.swf::Doppler%20Shift%20Interactive
Simulation 2: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html
You may use the simulations to answer the pre lab quiz questions as well.
More info about the Doppler Effect is available at the following site: http://www.animations.physics.unsw.edu.au/jw/doppler.htm
For more info on Standing Waves check out this link: hyperphysics.phy-astr.gsu.edu/hbase/Waves/string.html
Pre-Lab Quiz is available at the course Blackboard website
Lab
This week you will be completing the Doppler Effect lab (pg. 71) and the Driven Harmonic Oscillator: Waves on a String lab (pg. 75) found your lab manual.
We will be using digital simulations, Capstone software, and a driven harmonic oscillator to complete this lab.
We will be using digital simulations, Capstone software, and a driven harmonic oscillator to complete this lab.
Post Lab
Please post a reflection on these lab experiences on the Waves Lab Reflection discussion board on the course Blackboard site.
Be sure to include for BOTH labs:
Be sure to include for BOTH labs:
- What you did
- Why you did it
- Any interesting observations
- What you learned from doing the lab