# 1-5 Waves Question1. A water wave has a wavelength of 4.0 m and a speed of 2.0 m/s. What is the period of this wave? 2. When I was a teenager like you, we listened to records that would turn on...

1-5 Waves Question

1. A water wave has a wavelength of 4.0 m and a speed of 2.0 m/s. What is the period of this wave?

2. When I was a teenager like you, we listened to records that would turn on phonographs. The phonograph record has a groove in which the needle would sit. As the record turns, a certain groove passes the needle at 25 cm/s. If the wiggles in the groove are 45 μm apart, what is the frequency of the sound that results?

3. An observer from the beach see an anchored fishing boat rise and fall through a total range of

3.5 m once every 4 s as the waves whose crests are 25 m apart pass it. Find (a) the frequency of the waves, (b) the velocity of an individual water molecule at the surface.

4. Waves travel from deep water to shallow water. If the speed of the wave is 20.0 cm/s in the deeper water, and 0.12 m/s in the shallower water, what is the index of refraction? (Hint: use the ratio of v1/v2 = n to solve)

5. Last year I felt an earthquake while I was watching television. The earthquake that I experienced produced a wave that travelled through the earth at a speed of 1.3 X 104 m/s. This wave is incident on a boundary between two types of materials. If this incident angle is 35o and the refracted angle is the second medium is 32o, what is the speed of the wave in the second medium? (Hint: use the ratio of v1/v2 = n to solve)

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### 1 Answer

You are only supposed to ask one question at a time. So I will answer the first question only.

If the velocity, v = 2.0 ms-1

and wavelength = 4.0 m

Water wave is also a sinusoidal wave, for a sinusoidal wave,

V = wavelength x frequency = L x f

f = 1/T where T = period.

therefore,

v = L/T

T = L/v

T = 4.0m/2.0 ms-1

T = 2 s.

The period is 2 seconds.