Unit 7 Lesson 4 Check

10.  An airplane is flying overhead at a speed of 100.0 m/s. The engines of the plane emit a sound whose frequency is 1000. Hz. The speed of sound is 340. m/s.

A.    What frequency sound do you hear when the plane is flying towards you?

• 1000 Hz

• 1417 Hz

• 773 Hz

• 0 Hz

10.  An airplane is flying overhead at a speed of 100.0 m/s. The engines of the plane emit a sound whose frequency is 1000. Hz. The speed of sound is 340. m/s.

B. What frequency sound do you hear when the plane is flying away from you?

• 1000 Hz

• 1417 Hz

• 773 Hz

• 0 Hz

10.  How do we know that the universe is expanding?

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15.  When a wave source moves toward a receiver, does the receiver encounter an increase in wave frequency, wave speed, or both?

• Increase in wave frequency only

• Increase in wave speed only

• Increase in both wave frequency and wave speed

20.  If you encounter a sonic boom, is that evidence that an aircraft of some sort exceeded the speed of sound moments ago to become supersonic? Defend your answer.

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20.  Astronomers find that light coming from point A at the edge of the sun has a slightly higher frequency than light from point B at the opposite side. What do these measurements tell us about the sun’s motion?

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