SLINKY LAB
READ AN ANNOTATE (10 pts)
Longitudinal versus Transverse Waves versus Surface Waves
One way to categorize waves is on the basis of the direction of movement of the individual particles of
the medium relative to the direction that the waves travel. Categorizing waves on this basis leads to
three notable categories: transverse waves, longitudinal waves, and surface waves.
A transverse wave is a wave in which particles of the medium move in a direction perpendicular to
the direction that the wave moves. Suppose that a slinky is stretched out in a horizontal direction across
the classroom and that a pulse is introduced into the slinky on the left end by vibrating the first coil up
and down. Energy will begin to be transported through the slinky from left to right. As the energy is
transported from left to right, the individual coils of the medium will be displaced upwards and
downwards. In this case, the particles of the medium move perpendicular to the direction that the pulse
moves. This type of wave is a transverse wave. Transverse waves are always characterized by particle
motion being perpendicular to wave motion.
A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the
direction that the wave moves. Suppose that a slinky is stretched out in a horizontal direction across the
classroom and that a pulse is introduced into the slinky on the left end by vibrating the first coil left
and right. Energy will begin to be transported through the slinky from left to right. As the energy is
transported from left to right, the individual coils of the medium will be displaced leftwards and
rightwards. In this case, the particles of the medium move parallel to the direction that the pulse
moves. This type of wave is a longitudinal wave. Longitudinal waves are always characterized by
particle motion being parallel to wave motion.
Problem: Can transverse waves and longitudinal waves of the same amplitude have the same frequency.
5 Hypothesis: Transverse and Longitudinal waves of the same amplitude (will or will not) have the same
frequency.
10 Rationale:
Experiment: Create longitudinal waves by stretching the spring about 1 meter and hitting one end.
After hitting the end watch as the wave goes across the spring. Measure the amplitude by measuring the
distance of the section of coils that move together (compressions). Attempt to make 10 waves in 10 sec. This
will create frequency of 1 wave per second.
Create a transverse wave by having two people hold the slinky and one person waving his arm up and
down. Attempt to make 10 waves in 10 seconds. Measure the amplitude by measuring the distance from rest
to the crest of the wave.
(10) Record your data below:
Wave
Frequency
Amplitude
Longitudinal
1 hertz
4.2 cm
Transverse
1 hertz
6 cm
(5) Analysis: Create a Bar Graph for the different amplitudes on the back of the paper
(10) Identify the trend in your graph
(10) Conclusion:
Problem 2: Which form of interference reflection or refraction will have a greater effect on the speed of the
wave.
5 Hypothesis: (Reflection or Refraction) will reduce the speed of the wave the most.
10 Rationale:
Experiment: Create a longitudinal wave like you created in experiment 1. Time how long it takes the wave to
travel 1 meter. Then create a bend in the direction of the coil and time how long a wave of the same
amplitude (power) takes to travel the length of the slinky. Finally straighten the slinky and place a book at the
opposite end to see how long it takes to travel when it is reflected back.
10 Data
WAVE
Regular
Refracted
Reflected
Distance
1m
1m
1m
Time (s)
3 sec
3.6 sec
3.1 sec
Speed (m/s
(5) Analysis: Create a Bar Graph for the different wave speeds on the back of the paper
(10) Identify the trend in your graph
(10) Conclusion: