1. Waves, Periodic Motion, and Simple Harmonic Motion

2. Mass on a Spring We are going to start by graphing the motion in the activity from last time. Please sketch your ideas… What should the x and y axes represent? Which axis should represent height and which should represent time? Why?

3. Equilibrium The “resting position” is what we call equilibrium It’s where the net force on the object is equal to zero

4. Periodic Motion and Simple Harmonic Motion A repeated motion, such as this spring mass systems motion or a child swinging on a swing, is called a periodic motion Simple Harmonic Motion describes any periodic motion that is the result of a restoring force that is proportional to displacement

6. Wave Vocabulary Amplitude: The maximum displacement from equilibrium Period (T): The time it takes a complete cycle to occur Frequency (f or ν): the number of cycles or vibrations per unit time units: hertz = s -1 Wavelength (λ): The length of one cycle (we’ll come back to this)

7. These are graphs showing a thing moving up and down. The horizontal axis represents time and the vertical axis represents position. A B C D Rank these from lowest frequency to highest frequency

8. These are graphs showing a thing moving up and down. The horizontal axis represents time and the vertical axis represents position. A B C D Rank these from smallest amplitude to largest amplitude by writing the letters A B C and D in the blanks:

9. Pendulums A mass suspended at the end of a string is a simple pendulum. The time of a back-and-forth swing of the pendulum is its period. Galileo discovered that the period of a pendulum depends only on its length—its mass has no effect.

11. Foucault’s Pendulum In 1851, French physicist Léon Foucault used a pendulum to prove that the Earth turns. His Pendulum hangs from the dome of the Panthéon in Paris. It has a length of 67 meters. What was the period of his pendulum? What is the frequency of his pendulum?

13. There is another Foucault pendulum at the Museum of Science and Industry in Chicago Watch the video with a timer. https://www.youtube.com/watc h?v=iqpV1236_Q0 https://www.youtube.com/watc h?v=iqpV1236_Q0 What is the period of the pendulum? What is the length? What is the frequency?

14. Frank Oppenheimer demonstrates that a pendulum swinging back and forth traces out a straight line over a stationary surface, and a sine curve when the surface moves at constant speed.

15. Most information gets to us in some form of wave. Sound is energy that travels to our ears in the form of a wave. Light is energy that comes to our eyes in the form of a different kind of wave (an electromagnetic wave). The signals that reach our radio and television sets also travel in the form of electromagnetic waves.

16. When energy is transferred by a wave from a vibrating source to a distant receiver, no matter is transferred between the two points. Think about the very simple wave produced when one end of a horizontally stretched string is shaken up and down. Each part of the string moves up and down and the disturbance moves horizontally along the length of the string. The disturbance moves, not parts of the string itself.

17. Drop a stone in a quiet pond and you’ll produce a wave that moves out from the center in an expanding circle. It is the disturbance that moves, not the water.

18. Suppose you create a wave along a rope by shaking the free end up and down. The motion of the rope is at right angles to the direction in which the wave is moving. Whenever the motion of the medium is at right angles to the direction in which a wave travels, the wave is a transverse wave.

19. Sometimes the particles of the medium move back and forth in the same direction in which the wave travels. When the particles oscillate parallel to or along the direction of the wave, the wave is a longitudinal wave.