Transverse and Longitudinal Waves

Transverse and Longitudinal Waves Physical Science Pablo Hanna 2022 Name: ___________________________________________ Period: ________ Date: _________ Essential Question: How is transverse wave different from longitudinal wave? Two kinds of waves: transverse and longitudinal Suppose a piece of wood is floating on the surface of a pond. You throw a rock into the pond and create a ripple of waves. The waves move outwards from where the rock hit. When the waves pass the wood, it bobs up and down. The wood does not move in the same direction as the wave is moving, but rather it moves in a direction perpendicular (vertical; straight up and down; upright) to the travel of the wave, i.e. transverse. In the case of the falling dominoes, the movement of the dominoes was in the direction parallel to the movement of the wave, i.e. longitudinal. Another example of a longitudinal wave is a P wave or primary wave during an earthquake. P waves are also known as compressional waves, because of the pushing and pulling they do. Sound waves are longitudinal. When we speak, the vocal cords vibrate the air, setting it into motion. The molecules of air vibrate in the same direction as the vibration of your vocal cords. These molecules in turn vibrate the molecules next to them, and so on. The region in which the molecules get pushed becomes more dense then the region around it, because more molecules are there. The increased density pushes these neighboring molecules further ahead and the sound travels. This sort of longitudinal wave is also called a pressure or compression wave. Earthquakes can also be compression waves. One of the things that I study is to compress crystals and see how the atoms respond. The ease in which a material can be compressed is related to the speed in which sound waves can travel through it. For instance, diamond is very incompressible, and sound waves, or compression waves, travel through it very fast. The speed of sound in air varies depending upon the temperature or density of the air. Hot air has lower density and therefore sound travels slower. Sound travels faster through cold air. Amplitude is not tied into the equation relating the other 3 wave parameters. It can be anything it wants to be. The amplitude of a sound wave is how loud the sound is. The unit of measurement for the amplitude of a sound wave is called decibels. For an earthquake, the Richter scale measures the amplitude. The greater the amplitude the greater the displacement of the earth, and the greater the damage. Clarifying Questions: 1. What are the two types of waves? The two types of waves are transverse waves and longitudinal waves. _____________________________________________________________________________________ _____________________________________________________________________________________ 2. What happens when you throw a rock on a pond? When you throw a rock on a pond, it creates ripples that spread outwards in concentric circles. _____________________________________________________________________________________ _____________________________________________________________________________________ 3. What does it mean by perpendicular? Perpendicular means forming a right angle or 90-degree angle. _____________________________________________________________________________________ _____________________________________________________________________________________ 4. What is a transverse wave? A transverse wave is a wave in which the displacement of the medium is perpendicular to the direction of _____________________________________________________________________________________ propagation of the wave. _____________________________________________________________________________________ 5. Why are falling dominoes an example of longitudinal wave? Falling dominoes create a longitudinal wave because the disturbance ____________________________________________________________ ____________________________________________________________________________________ (the falling dominoes) travels parallel to the direction of wave propagation. 6. Draw and label a transverse wave 6. Draw and label a longitudinal wave 7. Why is sound wave considered as a longitudinal wave? Think! Sound waves are considered longitudinal waves because they propagate through compression and _____________________________________________________________________________________ rarefaction of the medium, with the particles of the medium oscillating parallel to the direction of wave propagation. _____________________________________________________________________________________ 8. Why is earthquake as example of longitudinal-compressional wave? Think! Earthquakes are an example of longitudinal-compressional waves because they involve the propagation of energy _____________________________________________________________________________________ through compression and rarefaction of the Earth's crust, with particles of the medium moving parallel to the direction of wave propagation. _____________________________________________________________________________________ 9. What determines the speed of sound in air? The speed of sound in air is determined by factors such as temperature, humidity, and the composition of the air. _____________________________________________________________________________________ 10. Why do sound travel faster in cold air? Explain. Think! Sound travels faster in cold air because cold air is denser than warm air, which allows sound waves to propagate _____________________________________________________________________________________ more efficiently due to the increased number of air molecules per unit volume. _____________________________________________________________________________________ 11. What is amplitude? What is its unit? Amplitude is the maximum displacement or distance from the equilibrium position of a wave. Its unit is meters (m). _____________________________________________________________________________________ _____________________________________________________________________________________ 12. What is the relationship between amplitude and the displacement of the earth? The displacement of the Earth during an earthquake is related to the amplitude of the seismic waves produced. _____________________________________________________________________________________ Higher amplitude seismic waves correspond to larger displacements of the Earth's surface during an earthquake. _____________________________________________________________________________________