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TOPIC: EnergyAIM: Describe waves.
Do Now: (Take out your waves reading notes)
Review Question #1 on back of KE and PE reading notes
HW: CL Energy due Monday!
If both of these balls are traveling down a bowling lane at the SAME speed, which one would have more kinetic energy? Support your answer.
A pebble tossed into the water will create a circular disturbance which travels outwards in all directions. The pebble transfers some of its energy to nearby water molecules causing them to move. These water molecules transfer this energy to molecules around them…Energy is traveling in the form of a wave on the surface of the water.
Slinky waves can be made by vibrating the coil back & forth in either a horizontal or a vertical direction.
Mechanical
waves
•Require a medium • Ex: Sound waves• Sound can’t be heard
in outer space • Why???
–Bc outer space is a vacuum
The sound produced by the bell cannot be heard since sound can’t travel through a vacuum. It is a mechanical wave.
•Medium not needed –CAN TRAVEL THROUGH A VACUUM (no matter exists)
•Ex : light & radio waves, x-rays
Electromagnetic
waves
Direction of particles
Direction of wave
•Particles of medium move at RIGHT ANGLES to direction of the wave
(PERPENDICULAR)
Direction of wave
Direction of particles (left & right)
•Particles of medium move PARALLEL to the direction of the wave
(BACK AND FORTH)
•compression = where particles are close together
•rarefaction = where particles are far apart
rarefaction
compression
Forces in Earth’s crust can cause regions of the crust to shift, bend, or even break. The breaking crust vibrates, creating seismic waves that carry energy outward. Seismic waves are a combination of compressional and transverse waves. They can travel through Earth and along Earth’s surface. The more the crust moves during an earthquake, the more energy is released.
Let’s summarize…
1.What is a wave?
2.Describe the cause of waves.
3.Describe a medium.
4.Identify an example of a medium.
5.Describe a vacuum.
6.How do particles move through a medium?
7.Explain the difference between mechanical and electromagnetic waves.
8.Explain the difference between transverse and longitudinal waves.
Which of the following is the best example of a wave?
1.A stone rolling downhill
2.A vehicle moving on a bumpy road
3.A string vibrating on a guitar
4.A grasshopper jumping up and down
Which of the following statements applies to longitudinal waves?
1.The motion of the medium is random.
2.The motion of the medium is in a circular pattern.
3.The motion of the medium is parallel to the motion of the wave.
4.The motion of the medium is perpendicular to the motion of the wave.
Sound reaches our ears because sound makes particles
1.heat up.
2.slow down.
3.cool down.
4.vibrate.
The distance between the Earth and the moon was determined by measuring the time it took for light waves from the Earth to travel to the moon and back. Why was it not possible to use sound waves for this experiment?
1.Sound waves must move through a substance.
2.Sound waves change frequency on the return to earth.
3.Sound waves move too slowly for this technique to be accurate.
4.Sound waves move more slowly in the Earth’s atmosphere than in space.
A large spring is stretched horizontally between 2 people. One person wiggles the spring up and down at one end. The up-and-down vibration then moves along the spring on to the other person. Which of the following type of wave is created in the spring?
1.pressure wave
2.longitudinal wave
3.transverse wave
4.nonmechanical wave