SciencePhysics4.1 Reading Check & Understanding Key Ideas
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4.1 Reading Check & Understanding Key Ideas

Yoshiaki Lee avatar Yoshiaki Lee
25 July 2022
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10 test answers

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question
What is the difference between a crest and a trough?
answer
A crest is the highest point in a wave. A trough is the lowest point in a wave.
question
What are three ways to measure wavelength?
answer
A wavelength can be measured from crest to crest, trough to trough, or just by picking any part of the wave and measuring the distance to the same place on the next wave.
question
What property of a wave is measured in hertz?
answer
Frequency.
question
How are the wavelength and frequency of a wave related?
answer
The shorter the wavelength, the higher the frequency, and vice versa.
question
What is the difference between a transverse wave and a compression wave?
answer
A transverse wave is a wave in which matter in the medium move at right angles to the direction that the wave travels. A compression wave is a wave in which matter in the medium moves back and forth along the same direction that the wave travels.
question
You can make a wave by shaking the end of a long rope up and down. (a) Explain how you would shake the end of the rope to make the wavelength shorter. (b) State two different ways you could shake the rope to increase the energy carried by the wave.
answer
a) Shake the rope up and down more frequently. This will have an increase in frequency, therefore, the wavelength will be shorter. b) Increase the energy carried by the rope by increasing the side-to-side motion (increasing amplitude) or by shaking it faster (to increase the frequency).
question
Explain why water waves travelling under a raft do not move the raft horizontally.
answer
Water waves moving under a raft raise the raft higher and then lower as the crest and trough pass beneath it. The motion is 90º to the direction of the wave, so the raft moves only up and down.
question
A wave in the open ocean between Prince Rupert and Haida Gwaii has an amplitude of 15 m in a large storm. The wavelength is 1000 m. (a) How high will the crest of the wave be above a boat that is in the trough? (b) If the wave travels at a speed of 10 km per hour, how often will a wave pass under the boat?
answer
a) The crest will appear 30 m above the trough, or exactly twice the amplitude of 15 m. b) 10 km is 10 000 m and 1 h is 60 min. Therefore ten 1000 m waves will pass by in 60 min or 1 wave will pass every 6 min.
question
A student performs a frequency experiment on three different pendulums and obtains the following results: (a) Calculate the frequency of each pendulum in Hz. (b) Rank the pendulums from lowest to highest frequency.
answer
a) Pendulum A: 32 / 8 = 4 Hz Pendulum B: 72 / 9 = 8 Hz Pendulum C: 210 / 80 = 2.625 Hz b) Pendulum C, Pendulum A, and Pendulum B.
question
A female soprano sings at a higher frequency (higher pitch) than a male baritone. (a) Which singer is producing waves of longer wavelength? Explain your answer. (b) If both singers sing at an equal volume, which singer is sending more energy out through his or her voice? Or are they both sending out the same energy? Explain your answer.
answer
a)The male is producing waves of longer wavelength. This is because the female sings at a higher frequency, therefore, the wavelength produced by her voice is shorter than that produced by the male baritone. b) At an equal volume, the singer with the higher frequency (higher pitch) sends out more energy. Every vibration sends out energy, and the higher pitch sends it more frequently..