Question

Please answer the questions fully and dont copy what was answered earlier on a previous post please

Lab 21 Part 1:

Materials- Slinky, Partner

Methods- A slinky was spread out 15 feet long with a partner and I sitting on the floor. Each of us was only holding a couple of coils while the rest was on the ground. Then each person sent over waves of different sizes and observed the different speeds that they passed by. Afterwards each person sent over transverse waves by moving the slinky side to side. Then we observed longitudinal waves by pushing the slinky in and pulling back.

            After that the partner sent a transverse wave and the same time as me. It was observed what happens when the waves pass each other. Then moving waves were made by moving one end of the slinky back and forth while the partners end was still to create standing waves.

1. What happened when the transverse waves reached your partner’s end? Did the reflected wave stay on the same side as the one you sent? Draw a diagram showing the incoming and reflected waves. 2. Did the waves go any faster or slower when you tried a variety of amplitudes? Explain how this agrees or disagrees with the equation for a transverse wave’s velocity. 3. What did you notice about the speed of the longitudinal waves compared to the transverse waves? 4. Explain what happened when you and your partner both sent waves on the same side. What kind of interference took place? 5. What happened when waves on opposite sides passed each other? 6. How did shortening the length of the spring affect the resonant frequencies? How does this confirm the relationship v = λ f when velocity is constant? (Hint: a shorter spring length means smaller wavelengths for each standing wave). 7. Using this knowledge, explain how musical instruments create higher and lower tones. Use a string instrument as an example.

Answer 1

1. The transverse wave is reflected back but changes phase by 180 degree. Friend rigidly holds it, hence acts as a denser medium. The reflected wave will appear on opposite side as shown.

2. The waves did not change its velocity as velocity is independent of the amplitude of wave.

The velocity of a transverse wave is given by where T is the tension and mu is the mass density. So velocity is supposed to be independent of amplitude

3. This is to be answered by you based on what you saw in the experiment.

4. If the waves were created such that they met on the same side (in phase), the amplitude increased. This is called constructive interference.

5.If the waves where out of phase (opposite side) the amplitude decreases and the process is known as destructive interference.

6. The shortening of the length of the spring increased the resonant frequency, as expected from the equation v = λ f . A shorter spring length means smaller wavelengths for each standing wave, the velocity is constant, so the frequency increases.

7. In musical instruments, example guitar, by pressing the wire at different point we can change the length. If we keep a larger length we wil have lower resonant frequency (tone) and vice versa.