Physics Chapter 5 Section 3

Sounds in strings revisitedSounds in strings revisited

Mar 2nd, 2012HW: 5.3 PTG, p 517 #1-5, Due Tuesday Learning Objective

Explain direct and inverse relationships Explain how wave speed, wavelength, and

frequency are related Create a data table to organize data for

experiments. Success Criteria

Describe what determines wavelength and sound

Describe the relationship between tension and speed of a wave

Describe the relationship between wavelength and frequency

Determine the velocity of a wave using the equation

Calculate wavelength of a standing wave Describe how the pitch of the sound produced by

a vibrating string depends on the wave speed, wavelength and frequency of the waves on the string.

Do Now: Finish Vocab

Boxes 5.2 Quiz Write LO and

SC on new left page

WDYS/WDYT on page 508

Agenda Do Now Investigation

5.3 Summary/Exit

Ticket

Mar 2nd, 2012HW: 5.3 PTG, p 517 #1-5, Due Wed. Learning Objective

Explain direct and inverse relationships Explain how wave speed, wavelength, and

frequency are related Create a data table to organize data for

experiments. Success Criteria

Describe what determines wavelength and sound

Describe the relationship between tension and speed of a wave

Describe the relationship between wavelength and frequency

Determine the velocity of a wave using the equation

Calculate wavelength of a standing wave Describe how the pitch of the sound produced by

a vibrating string depends on the wave speed, wavelength and frequency of the waves on the string.

Do Now: Finish data

table and notebook layout for 5.3 #1-7

Agenda Do Now Investigation

5.3 Summary/Exit

Ticket

Investigate

Read procedures 1-7 Lay out notebook and create data

table for #4-6 Make spaces to answer questions 7-

8

Sample Data Table

String Length Wavelength(2x string length)

Pitch (high, low, or medium)

Investigate 5.3 (Guidelines for 1-7)

Same set-up as Investigation 1

What kind of wave is the string making?

How do you calculate wavelength?

Standing Wave - this is similar to the waves made in the spring

The wavelength is twice the length of the string

Investigation 5.3 (Guidelines for 8-12)

Complete with your group

Remember that speed is distance traveled over a period of time.

Summary/Exit Ticket

How does changing the wavelength effect the velocity?

How does changing the frequency effect the velocity?

Mar 3rd, 2012HW: 5.3 PTG, p 517 #1-5, Due WednesdaySign up for Honors Meetings!

Learning Objective Explain direct and inverse relationships Explain how wave speed, wavelength, and frequency

are related Create a data table to organize data for experiments.

Success Criteria Describe what determines wavelength and sound Describe the relationship between tension and speed

of a wave Describe the relationship between wavelength and

frequency Determine the velocity of a wave using the equation Calculate wavelength of a standing wave Describe how the pitch of the sound produced by a

vibrating string depends on the wave speed, wavelength and frequency of the waves on the string.

Do Now: If you keep the

wavelength the same, how can you change the velocity of the wave?

Agenda Do Now Notes 5.3 Summary/Exit

Ticket

Physics Talk 5.3

What kind of wave does the vibrating string produce?

How do you calculate the wavelength?

A standing wave

The wavelength is twice the length of the string

Physics Talk 5.3

How does frequency relate to pitch?

Equation for wave speed

The higher the frequency, the higher the pitch

Wave speed = wave frequency x wavelength

Physics Talk 5.3

How do we solve for frequency?

Rearrange the equation to read

Physics Talk 5.3

What happened when you shortened the length of the string?

How is this shown in the equation?

The wavelength was shortened

Pitch increased Frequency increased

Dividing by a smaller number on the bottom, gives us a larger frequency If you have to share

something with fewer people, you get more

http://www.youtube.com/watch?v=HpovwbPGEoo

http://www.youtube.com/watch?v=LDekBnEqTUk&feature=related

http://www.youtube.com/watch?v=n-D3tsZIoZ8&feature=related

http://www.youtube.com/watch?v=YAh4-4UPr64&feature=related

Physics Talk 5.3

What kind of mathematical relationship does this show?

What is an inverse relationship?

Inverse Relationship

A relationship where when one value increases, the other decreases, or as one value decreases, the other increases

Physics Talk 5.3

How is frequency an example of an inverse relationship?

Decreasing the wavelength increases the frequency

Physics Talk 5.3

How are tension and pitch related?

Since the wavelength did not change, and the frequency increased, this means the wave speed increased

An increase in tension, produces a larger force, which leads to a larger acceleration on the string (F=ma)

Physics Talk 5.3

How are tension and pitch related? (continued)

When the force accelerates the string, the wave speed increases and the string vibrates faster

Since the wave is faster, the frequency must also be faster, leading to a higher pitch

Physics Talk 5.3

What is a direct relationship?

Example of direct relationship

A relationship where as one value increases, the other value also increases

Increasing the wave speed also increases the frequency and pitch

Physics Talk 5.3

How does increasing the thickness of the string lead to a different pitch?

When the string is larger, it has a greater mass for the wave to travel through

This also means it takes more force to stop the string from vibrating

The force is the tension in the string

Physics Talk 5.3

How does increasing the thickness of the string lead to a different pitch?

Since the mass is heavier, the acceleration will be less (F=ma)

This creates a slower wave speed

Decreasing wave speed will decrease the frequency and pitch

Physics Talk 5.3

When do standing waves occur?

How does string length related to standing waves?

When the length of the coiled spring or string has a certain relationship

The length much be 1/2, 1, 3/2, 2, etc of the wavelength

Physics Talk 5.3

Equation for standing waves

Standing waves occur when the following equation is met:

L = string lengthn = the number of

antinodes (crests)Lambda = wavelength

Physics Talk 5.3

How do you calculate the period for a wave?

How is a period related to the frequency?

T is the period

The frequency is the reciprocal of the period

Sample Problems 1 and 2 p 513 Use GUTS When in doubt, draw it out

Pictures are very helpful!

LO and SC reflection Learning Objective

Explain direct and inverse relationships Explain how wave speed, wavelength, and frequency are

related Create a data table to organize data for experiments.

Success Criteria Describe what determines wavelength and sound Describe the relationship between tension and speed of a

wave Describe the relationship between wavelength and frequency Determine the velocity of a wave using the equation Calculate wavelength of a standing wave Describe how the pitch of the sound produced by a vibrating

string depends on the wave speed, wavelength and frequency of the waves on the string.

January 19, 2011Sign up for Honors Meetings!

Learning Objective Explain direct and inverse relationships Explain how wave speed, wavelength, and frequency

are related Create a data table to organize data for experiments.

Success Criteria Describe what determines wavelength and sound Describe the relationship between tension and speed

of a wave Describe the relationship between wavelength and

frequency Determine the velocity of a wave using the equation Calculate wavelength of a standing wave Describe how the pitch of the sound produced by a

vibrating string depends on the wave speed, wavelength and frequency of the waves on the string.

Do Now: Finish LO and

SC Reflections Essential

Questions, pg. 516

What does it mean?

How do you know?

Why should you care?

Agenda Do Now Summary Quiz

Essential Questions-pg. 516 What does it mean? How do you know? Why should you care?