Wave speed powerpoint 615

Happy Tuesday!

June 15, 2015 • Today’s Agenda: • Notes • Prac/ce • Exit Ticket

Today’s Objec.ves PSc.3.2.1:

• Can recognize the rela/onship between period & frequency • Can exemplify wave energy as related to its amplitude • Can explain the rela/onship among velocity, frequency, & wavelength and use it to solve wave problems: vw=fλ (WS = WL x F)

Lesson overview • Build on understanding of waves & their proper/es by learning how to calculate wave velocity/speed based on a wave’s frequency & wavelength.

• Yesterday, you learned how to ID & classify waves • Today, you will con/nue learning about wave proper/es and will prac/ce measuring wavelength & determining frequency to calculate wave velocity • You will take an exit /cket

Interactive notebook • Glue in notes on pg. 101 in your interac/ve notebook

Catalyst/prompt • What is a mechanical wave?

• What are the three types and what are their physical proper.es?

Review/answers • A mechanical wave is a wave that carries energy through a medium, which can be a solid, liquid, or gas • The three types of mechanical waves are: transverse, longitudinal/compression, and surface waves

Waves review • A transverse wave is a wave that carries energy perpendicular to the mo/on of the medium

• A longitudinal/compressional wave is a wave that carries energy parallel to the mo/on of the medium

compression

rarefac.on

Waves review • A surface wave separates two media and moves in a circular mo/on – Like a bobber in the ocean

period • The /me required for one cycle, a complete mo/on that returns to its star/ng point, is called the period

frequency • Any periodic mo.on has a frequency, which is the number of complete cycles in a given /me

frequency • Frequency is measured in hertz (Hz)

Frequency & energy • Frequency depends on energy • The more energy, the higher the frequency • The less energy, the lower the frequency

Amplitude & energy • Amplitude & energy are directly propor/onal • The more energy, the greater the amplitude

Frequency & wavelength • Frequency & wavelength are inversely propor/onal • When frequency increases, wavelength decreases • When frequency decreases, wavelength increases

Wave speed • Wave frequency x wavelength = wave speed formula

Wave Speed = wavelength x frequency

Wave speed: practice

a l u Wave Speed = wavelength x frequency m r fo 1) 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? Wave Speed = wavelength x frequency Plug in the #s: Wave Speed = _0.25 ___ x _3.0 __ = _0.75 ______ m/s

Wave speed: practice 2) A wave on a rope has a wavelength of 2.0m and a frequency of 2.0Hz. What is the speed of the wave?

Formula? Wave Speed = wavelength x frequency Plug in the #s: Wave Speed = _2.0 __ x _2.0 __ = _ 4______ .0 m/s

you try! Practice • Complete #3-­‐10 on your worksheet • Show your work • You may work with a partner or independently • You have 15 minutes • I will ask for volunteers to explain how they found their answers when /me is called • Raise your hand if you have a ques/on

Exit ticket pg. 102 1. Define period in regards to a wave’s mo/on.

2. In 1-­‐2 sentences, describe how frequency is related to wavelength.

3. How is a wave’s amplitude affected when more energy is applied to the medium?

4. A wave has a frequency of 50 Hz and a wavelength of 10m. What is its speed?

5. A wave has a wavelength of 10m and a speed of 340 m/s. What is its frequency?