Problem: How is a transverse wave in a coiled spring transmitted and reflected ?

Materials:
long spiral spring

Procedure:
1) With the help of your partner, stretch the spring to a length of approximately 5 meters on a smooth, clean floor. Your partner should hold one end of the spring rigid throughout this experiment.

2) Create a pulse at your end of the spring by moving your hand quickly from the rest position to one side and back to the rest position, at right angles to the length of the spring.

3) Describe the motion you observed of a point near the middle of the spring as the pulse passes.

4) Move your hand in such a way as to generate single pulses with different amplitudes. Doest the amplitude of a pulse changes as the pulse moves from one end of the spring to the other?

5) Generate two pulses, one right after the other. Note how the distance between them changes as they mover along the spring . What does this tell you about the speed of the pulses? Generate two more pulses, close together and one distinctly larger than the other. How does the amplitude of each pulse affect its speed?

6) Stretch the string 2 meters farther. How is the speed of each pulse affected by the change in the tension of the spring?

7) During the investigation, the pulse you generated at the free end of the spring were "reflected" from the fixed end. Compare the reflected pulses with the original pulses.

8) Suspend the spring vertically from a high point in the room so that it stretches close to, but does not touch the floor. Avoid obstructions, since the spring must move freely along its whole length. Generate a transverse pulse at the top of the spring. Note whether the pulse is inverted when it is reflected from the free-end of the spring . Compare the properties of fixed-end reflections and free-end reflections.







OBSERVATIONS
TRANSVERSE WAVES

-As I was observing a point near the middle of the spring as the pulse passed, I noticed that the transverse waves that we were creating had crests ( high points) and troughs ( low points).

- The amplitude of a pulse change as the pulse moves from one end of the spring to the other did not change because the floor which we were experimenting on was smooth. If it had been concrete, the amplitude would have decreases as it traveled through the medium, due to friction.

- When we stretched the spring an extra 2 meters, the speed of each pulse decreased because of the change in the tension of the spring.

- Reflected pulse versus original pulse: There was no inversion, the crests were reflected as crest and troughs as troughs. The speed remained constant because the medium was the same.

- When we generated transverse pulse at the top of the spring, we noticed that the pulse was inverted when it was reflected from the free end of the spring. A fixed end reflection is when the pulse in inverted. A crest is reflected as trough and a trough is reflected as a crest. A fee end reflection, on the other hand is a pulse with no inversion-crests are reflected as crests and toughs as troughs. Both types of reflections have a constant speed and there is no change in the frequency or wavelength.






Problem:
How is a longitudinal wave transmitted through a spiral spring?

Materials:
spiral spring
masking tape

Procedure:

1) With the help of your partner, stretch the spring out to a length of approximately 3 meters on a smooth, clean floor.

2) Attach masking tape tabs at six equally spaced points along the spring.

3) At one end of the spring compress approximately ten coils between your fingers.

4) Release the compressed coils and observe the motion of the masking tape tabs as the pulse travels along the spring. Repeat this procedure a number of times, until the motion of the tabs is easily observed.

5) Place your hand in the coils at one end of the spring, and move your hand forward quickly. Note the motion of the tabs. Now, move your hand back quickly, and again note the motion of the tabs.

6) Move your hand back and forth quickly at a uniform frequency. Watch the series of pulses as it travels down the coil. Note the