mastering physics- change of phase (temperature), sound lab

5/4/13 Lab 13 (change of phase, sound)

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Lab 13 (change of phase, sound)

Due: 8:55pm on Sunday, April 21, 2013

Note: To understand how points are awarded, read your instructor's Grading Policy.

Interactive Figure: Change of Phase

Explore the Interactive Figure to help you with the following set of questions. If you need more help, click on"How To Use" for more information.

Instructions: Click the “Start” button, and observe what happens. To return to the starting point, click“Reset” at any time.

Part A

What happens when you heat ice that is at -40 C?

Hint 1. Heat and change in internal energy

The ice absorbs the heat. How would that affect the internal energy of the ice? How would thataffect the temperature of the ice?

ANSWER:

Correct

PHY110ASPRING2013

Lab 13 (change of phase, sound) Resources

The temperature stays constant.

The temperature increases forever.

The temperature increases until the ice reaches its melting point.

Signed in as Ellie Kamens Help Close



Part B

What happens when you heat ice that is at 176 C?

Hint 1. Energy for melting the ice and temperature

The melting point of ice is 0 C. When you heat ice at that temperature, all of the energy you supply

is used to melt the ice. What would then happen to the temperature of the ice?

ANSWER:

Correct

Part C

What happens when you heat water that is at 0 C?

Hint 1. Energy for boiling the water and temperature

Adding heat to water makes the molecules move faster by providing them with more energy. Whatwould that do to the temperature?

ANSWER:

Correct

Part D

What happens when you heat water that is at 100 C?

Hint 1. Energy for boiling the water and temperature

The temperature increases until all of the ice is melted.


The temperature stays constant until all the ice is melted.

The temperature stays constant forever.

The temperature does not change.

The temperature increases until it reaches 100 C.




When you heat water that is at 100 C, its boiling point, all of the energy you supply is used to boil

the water. What would then happen to the temperature of the water?

ANSWER:

Correct

Vibrational Motion and Waves Tutorial

Work through the tutorial by clicking the image or link below, then answer the questions below.Vibrational Motion and Waves

Part A

A 5-kg mass is attached to a spring and is oscillating with a period of 2 seconds and an amplitude of 5cm. If the amplitude is made to be 10 cm, the period of oscillation will be _____.

Hint 1. What determines the period of oscillation?

Does the period of oscillation depend on the mass and the spring’s stiffness?

ANSWER:


The temperature stays constant until all the water is boiled.

The temperature stays constant forever.

The temperature increases until all of the water is boiled.

2 seconds

less than 2 seconds

more than 2 seconds



Correct

The period of oscillation does not depend on the amplitude (it depends only on the mass and thespring’s stiffness).

Part B

Two blocks, one with a mass of 10 kg and another with a mass of 5 kg, are hanging on identical springs. Ifboth blocks are displaced and released, which one will oscillate with a higher frequency?

Hint 1. Frequency versus period

Frequency is the number of oscillations per second and is the reciprocal of the period of oscillation.

ANSWER:

Correct

The spring is able to accelerate the 5-kg block more quickly than the 10-kg block, which causes thefrequency of oscillation to be higher (and the corresponding period of oscillation to be lower).

Part C

Which of the two waves shown in the figure has the longer wavelength?

Both blocks oscillate with the same frequency.

the 10-kg block

the 5-kg block



Hint 1. Wavelength versus amplitude

The wavelength is the distance it takes for the wave to complete one cycle (this is independent ofamplitude).

ANSWER:

Correct

Wave 2 has a higher amplitude, but both have the same wavelength.

Part D

Two waves with the same wavelength are moving to the right. Wave 1 is moving faster than wave 2. Whichwave has a higher frequency?

Hint 1. How to compare frequencies

For which wave would crests pass by an observer more frequently?

ANSWER:

Correct

The frequency is equal to the speed of the wave divided by the wavelength.

Part E

You are floating in the ocean, and waves with a wavelength of 12 meters are causing you to bob up anddown. If the waves are moving with a speed of 4 m/s, what is your frequency of oscillation?

Hint 1. How to calculate frequency

The frequency of a wave is equal to the speed divided by the wavelength.

wave 1

wave 2

Both have the same wavelength.

wave 1

wave 2

Both have the same frequency.



ANSWER:

Correct

The frequency is equal to the speed of the wave divided by the wavelength, or 4/12 Hz = 1/3 Hz.

Part F

An astronomer notices that radiation emitted by a star is slightly redshifted (the wavelength is longer). Thismeans that the star _________.

Hint 1. How do astronomers measure velocity?

Astronomers use the Doppler shift to determine how the star is moving.

ANSWER:

Correct

The Doppler shift causes light from objects moving away from us to be redshifted.

Part G

Suppose you are speeding through an intersection at 100 km/h and notice a policeman trying to measureyour speed using his Doppler gun, as shown in the figure. Because of the Doppler effect, the policemanwill measure a speed of __________.

3 seconds

4 cycles per second

0.33 cycles per second

0.25 cycles per second

is moving away from Earth

is moving toward Earth

is not moving



Hint 1. Doppler shift and velocity

The amount of the Doppler shift depends on the component of the velocity along a line connectingthe object with the observer.

ANSWER:

Correct

Since the velocity of the car is perpendicular to the direction from the car to the policeman, there is noDoppler shift.

Part H

Red light has a longer wavelength than blue light. Which type of light has a higher frequency? (The speedof light is independent of wavelength.)

Hint 1. How to determine frequency

Frequency is equal to the speed of a wave divided by the wavelength.

ANSWER:

more than 100 km/h

100 km/h

zero



Correct

Since frequency equals speed divided by wavelength, the smallest wavelengths have the highestfrequencies.

Video: Doppler Effect

Watch the video, and then answer the following questions.

Part A

When the bug is stationary and creating waves, how does the frequency of the wave some distance awayfrom the bug compare with the frequency of the vibration of the bug?

ANSWER:

red light

blue light

Both have the same frequency.



Correct

Part B

When the bug that is creating waves swims in the direction of the waves, how does the speed of the wavesome distance away in front of the bug compare with the speed of the wave created by a stationary bug?

Hint 1. What to look for in the video

Please watch the video again, and listen specifically to the part when Dr. Hewitt talks about the bugthat is swimming toward the right.

ANSWER:

Correct

Part C

When the bug that is creating waves swims forward, how does the frequency of the wave some distanceaway in front of the bug compare with the frequency of the wave produced by a stationary bug?

Hint 1. What to look for in the video

Please watch the video again, and listen specifically to the part when Dr. Hewitt talks about the bugthat is swimming toward the right.

ANSWER:

The frequency of the wave some distance away is less than the frequency of the vibration of thebug.

The frequency of the wave some distance away is greater than the frequency of the vibration ofthe bug.

The frequency of the wave some distance away is equal to the frequency of the vibration of thebug.

The speed of the wave some distance away is greater than the speed of the wave due to astationary bug.

The speed of the wave some distance away is less than the speed of the wave created by astationary bug.

The speed of the wave some distance away is equal to the speed of the wave due to a stationarybug.



Correct

Part D

When the bug that is creating waves swims forward, how does the frequency of the wave some distanceaway behind the bug compare with the frequency produced by a stationary bug

ANSWER:

Correct

Score Summary:

Your score on this assignment is 88.9%.You received 2.67 out of a possible total of 3 points.

The frequency of the wave some distance away in front of the bug is greater than the frequencyproduced by a stationary bug.

The frequency of the wave some distance away in front of the bug is equal to the frequencyproduced by a stationary bug.

The frequency of the wave some distance away in front of the bug is less than the frequencyproduced by a stationary bug.

The frequency of the wave some distance away behind the bug is less than the frequency of thewave produced by a stationary bug.

The frequency of the wave some distance away behind the bug is equal to the frequency of thewave produced by a stationary bug.

The frequency of the wave some distance away behind the bug is greater than the frequency ofthe wave produced by a stationary bug.

mastering physics- change of phase (temperature), sound lab

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