Four waves are described by the following expressions, where distances are measured in meters and times in seconds
I y = 0.12 cos(3x - 21t)
II y = 0.15 sin(6x + 42t)
III y = 0.13 cos(6x + 21t)
IV y = -0.23 sin(3x - 42t)
Which of these waves travel in the +x direction?
A)
I and II
B)
I and III
C)
II and IV
D)
I and IV
E)
II and III
D
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A) the natural laws that operate today are different than those that have operated in the past. B) sediments are laid down layer upon layer with younger layers always on the top. C) the processes and natural laws that operate today have been valid throughout geologic time. D) all rocks layers are originally uniform.
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A) vibrates. B) is boosted into higher energy levels. C) undergoes a frequency change. D) becomes frantic.
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A) coal. B) petroleum. C) natural gas. D) uranium.
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A) red light. B) blue light. C) green light. D) invisible.