Presentation on theme: " Chapter 17 Mechanical Waves & Sound. How does a disturbance produce waves? Procedure Fill a clear plastic container with water. Observe the surface."— Presentation transcript:
How does a disturbance produce waves? Procedure Fill a clear plastic container with water. Observe the surface of the water by looking down at an angle to the container. Use the pipet to release a drop of water from a height of 3 cm above the surface of the water. Repeat Step 2 with a drop released from each of these heights: 10, 20, 50, 60, 70, 90 cm. Create a table to record your observations after each drop. These observations will be QUALITATIVE (or descriptive, and not mumeric)
Analysis Questions Which drop produced the highest wave? Write a general statement (or conclusion) about how the distance a drop falls affects the wave produced in the container. Using your knowledge of energy, conservation of energy, and energy transfer, explain why the distance a drop falls affects the height of the wave produced. Thoroughly explain your answer.
Inquiry Activity How does a disturbance produce waves? P 499 Complete activity, answer questions as a group Submit one paper per group with all observations recorded and questions answered!
What are mechanical waves? Mechanical Wave A disturbance in matter that carries energy from one place to another Require a medium (or matter) in order to carry energy All waves carry energy!
What is a Medium? The material through which a wave travels Can be a solid, a liquid or a gas Space is NOT a medium Why?
How are mechanical waves created? A source of energy causes a vibration to travel through a medium
Types of Mechanical Waves Transverse Medium moves perpendicularly (or at right angles to the direction the wave travels) Longitudinal (Compressional) Medium moves parallel to the direction the wave travels
Transverse Waves Demos Rope (with ribbon attached) Student line (arms over shoulders)
Parts of a Transverse Wave Crest Highest point of the wave Trough Lowest point of the wave
Surface Waves A wave that travels along a surface that separates two media (or two types of matter) An object resting on a surface wave will move up and down, and back and forth These two motions result in a circular motion for the object
Frequency A periodic motion has a frequency Frequency The number of complete cycles in a given time For waves, this is the number of wave cycles that pass a point in a given time Measured in cycles per second, or Hertz (Hz)
Frequency & Wavelength As frequency increases, what happens to wavelength? Use the slinky at your table to determine the answer to this question, then respond using Socrative HINT: You can make either TRANSVERSE, or COMPRESSIONAL waves with your slinky
Socrative Questions… Two calculating frequency/ period questions
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Wave Speed REMEMBER v = d/t Think of one wavelength as DISTANCE Thin of period and TIME Wave Speed = wavelength / period OR Wave Speed = wavelength x frequency
Wave Speed Example One end of a rope is vibrated to produce a wave with a wavelength of 0.25 meters. The frequency of the wave is 3.0 Hertz. What is the speed of the wave? FORMULA Speed = Wavelength x Frequency