physicsa.com
 class code: SPS22 teacher: Mr. Elert classroom: A314 office: A214 test day: Friday phone: (718) 724–8500 ext. 2141 email: elert@midwoodscience.org

## Physics A: Problem Set 11: Interference and Superposition

 Barron's Let's Review: 11.7 Interference physics.info: Interference Wikipedia: Interference (wave propagation), Superposition principle HyperPhysics: Interference of Sound

### homework

1. Walking involves the coordinated periodic motion of various parts of your body. Identify the parts of your body that are moving…
1. in phase with each other
2. out of phase with each other
1. An arm and the opposite leg move in phase with one another. For example, when the right arm moves forward, the left leg does the same. The same is true for the left arm and right leg. When the left arm moves forward, the right leg does the same.
2. The arms of a walking person are out of phase with one another. When the right arm moves forward, the left arm moves backward. The same is true for the legs. When the right leg moves forward, the left leg moves backward. An arm and a leg on the same side of the body are also out of phase. When the right arm moves forward, the right leg moves backward. When the left arm moves forward, the left leg moves backward.

### in class activity

1. worksheet-superposition.pdf
These unusually shaped wave pulses are heading towards each other in a medium whose wave speed is one grid unit per second. Draw the resulting shape of the medium one, two, three, and four seconds later.
worksheet-superposition-key.pdf
The answer key is on a separate pdf.