Transverse & Reflected Pulses Created for CVCA Physics By Dick Heckathorn 16 May 2K+4

02 Transmitted and Reflected Pulses 16 Pulses on a “Frictionless” Slinky 28 Reflection and Refraction

Place the slinky on the floor and extend it so that it is under tension. Before doing this, ask instructor for some advice. Be careful not to over-extend the slinky, since this causes permanent damage.

Generate a pulse by giving the slinky a flick at right angles to the length of the slinky. Can you make different pulse shapes? Describe how you make different pulse shapes.

How fast do the pulses travel? Estimate the speed of the pulse. To do so, make the necessary measurements and calculations. Record your results.

Change the speed of the wave? Describe what you did to change the speed. Record them. Calculate the new speed.

Observe carefully what a specific point on a slinky is doing as a pulse goes by. You may wish to put a paper clip over one of the rings of the slinky to mark a point. Remove when done. Describe what you observe.

What is happening to the shape of the leading half of the pulse? To the trailing half of the pulse? Describe what you observe.

Make a pulse. Observe its propagation and then make a sketch of the pulse at one instant of time. Then make a sketch of the pulse a very, very short time later.

You have surely noticed that the pulse shape changes as it moves along the slinky. What do you think is happening here?

How would you expect the pulse to behave if the slinky were suspended so that it didn't touch the floor? What if it was suspended in water?

Make further observations of a single point or particle of the slinky as a pulse goes by from right to left. Sketch the left and right deflection of a particle as a function of time.

While observing the propagation of a pulse on the slinky, you may have noticed that the pulse does not vanish when it arrives at the far end. Describe what happens to the pulse as it is reflected.

Tie a two meter piece of string onto one end of the slinky and repeat #9. What do you observe?

That’s all folks!

Pulses on a “Frictionless” Slinky For this part of the experimentation, you will be watching two people investigate pulse phenomena on a slinky with very little friction.

Send a pulse from one end. Describe what happens to the pulse as it reflects from a held end?

2. Determine the speed of the pulse by first finding the time for the wave to travel from one end to the other and back to the original end.

The slinky is stretched to a greater length. Time the pulse from one end to the other and return.

How does the speed of the pulse in the further stretched slinky compare to the speed in the original length? Record measurements and results.

4. Identify and record the property(s) of a slinky which changed as it was stretched?

A pulse is sent from one end. Describe what happens to the pulse as it reflects from an end held by a long string?

Two similar pulses (same amplitude) are sent down the slinky, one from each end, oriented in the same direction, at the same time. Describe what one observes?

Does one pulse pass through or reflect from the other pulse? What might one do to find out? Describe what one can do and the result.

Set a pop can half way from both ends and a distance away from the slinky of between 1 and 2 amplitudes of the pulse. Send one pulse from each end with the orientation in the same direction. Describe what happens to the pop can. Explain why.

With the pop can in the same position, send one pulse from each end with the orientations in opposite directions. Describe the result.

That’s all folks!

Reflection & Transmission

Directions Tie a metal slinky and a plastic slinky together with some masking tape.

A. Metal Into Plastic With the system stretched, send a pulse from the metal slinky end. Describe its shape of the pulse as it moves down the metal slinky.

A. Metal Into Plastic 1. The wave reaches the point where the metal slinky and the plastic slinky are joined.

A. Metal Into Plastic Does any of the pulse continue into the plastic slinky? If yes, describe all the properties of the pulse.

A. Metal Into Plastic Does any of the pulse reflect back from the junction between the two slinkies? If yes, describe all the properties of the pulse.

A. Metal Into Plastic c. Describe the pulse in the plastic slinky after it reflects from the held end.

B. Plastic Into Metal With the system stretched, send a pulse from the plastic slinky end. Describe its shape of the pulse as it moves down the plastic slinky.

B. Plastic Into Metal 1. The wave reaches the point where the plastic slinky and the metal slinky are joined.

B. Plastic Into Metal Does any of the pulse continue into the metal slinky? If yes, describe all the properties of the pulse.

B. Plastic Into Metal Does any of the pulse reflect back from the junction between the two slinkies? If yes, describe all the properties of the pulse.

B. Plastic Into Metal c. Describe the pulse in the metal slinky after it reflects from the held end.

B. Plastic Into Metal Record any additional information you deem necessary.

That’s all folks!