Physics 2- Test One

What is the conversion from Hz to MHz?

1MHz = 1,000,000 Hz

What is the Doppler effect?

A change in sound frequency caused by motion of the sound source, motion of the listener, or both.

Give an example of a simple harmonic oscillator specially noting how its frequency is independent of amplitude.

A mass attached to a spring.

What is the difference between the velocity speed and the frequency of a wave? How do each affect wavelength?

A wavelength is directly proportional to the velocity speed of a wave and inversely proportional to the frequency of a wave.

At what point is the velocity of an object maximum in a spring motion?

At the origin of the object.

At what point is the acceleration of an object in a spring motion maximum?

Ate the maximum force and displacment.

What are the three categories of sound waves?

Audible waves, Infrasonic waves, and Ultrasonic waves.

When you hear a sonic boon you often cannot see the plane that made it why is that?

Because the aircraft would pass the observer before the sound reaches the ground. This is because the plane Is moving faster than sound in air.

T/F the speed of sound is slower in solids.

False

As you pass a freight truck with a trailer on a highway, you notice that its trailer is bouncing up and down slowly. Is it more likely that the trailer is heavily loader or nearly empty? Why?

If the mass is greater than the frequency would be smaller so it would be easier to notice by our eyes.

What are the ranges of each type of sound wave?

Infrasonic- <20Hz Audible - 20Hz-20,000Hz Ultrasonic- > 20,000Hz

Is the doppler shift real or just a sensory illusion?

It is real.

What is a waves intensity?

It is the power or energy of the wave transmitted per unit area.

If frequency is not constant for some oscillations can the oscillation be a simple harmonic motion?

No because that would mean the force on the object changes, which goes against Hooke's Law.

Define simple harmonic motion

Oscillatory motion where acceleration is directly proportional to displacement from equilibrium position, and always directed towards the equilibrium position.- Obeys Hooke's law

six members of a synchronized swim team wear earplugs to protect themselves against water pressure at depths, but they can still hear the music perform the combinations in the water perfectly. One day, they were asked to leave the pool so the dive team could practice a few dives and they tried to practice on a mat but seemed to have a lot more difficulty why might this be?

Since sound travels faster in water it aids in the hearing of the music.

What is the amplitude of an oscillatory motion?

The absolute max or min of the wave graph.

What are the main assumptions with the doppler effect?

The air is stationary, and all speed measurements are Meade relative to the stationary medium.

Define elastic potential energy.

The energy stored in a stretched object.

Define Hooke's Law

The force on an object should be equivalent to the restoring force.

Pendulum clocks are made to run at the correct rate by adjusting the pendulum's length. Suppose you move from one city to another where the acceleration due to gravity is slightly greater, taking your pendulum clock with you, will you have to lengthen or shorten the pendulum to keep the correct time, other factors remaining constant? Explain your answer.

The length of the pendulum would need to be increased because you would need to maintain the same length to gravity ratio.

What is the frequency of a wave and what units are used for it?

The number of complete cycles per unit time and Hz are commonly used.

What conditions must be met to produce simple harmonic motion?

The rate of change of velocity must be proportional to the displacement, also the direction should be towards the mean position.

What is the period of a wave?

The time it takes for a wave to complete one cycle

Some people modify cars to be much closer to the ground than when manufactured. Should they install differ springs? Explain your answer.

The user would install stiffer springs to prevent the car from hitting the ground.

Explain why you expect an object made of a stiff material to vibrate at a higher frequency than a smaller object made of a spongy material.

This would make the spring constant higher, which would correlate the the higher frequency.

T/F A wave will travel faster through an object with lower density.

True

At what point is the force maximum on an object in a spring motion?

When the position is maximum.

A community is concerned about a plan to bring train service to their downtown from the town's outskirts. The current sound intensity level, even though the rail yard is blocks away, is 70 dB downtown. The mayor assures the public that there will be a difference of only 30 dB in sound in the downtown area. Should the townspeople be concerned? Why?

Yes because according to the I=10log(I/Io) the intensity would be 1000 times the original.

Two identical waves undergo pure constructive interference. Is the resultant intensity twice that of the individual waves?

in pure constructive interference the resulting wave would be the amplitude of both waves combined.