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CTWaves-1. Is "The Wave" at the stadium a transverse wave or a longitudinal wave?
A) Transverse
B) Longitudinal
C) neither
Answer: Transverse
CTWaves-2.
A wave on a stretched drum head is an example of a
A) Transverse wave B) Longitudinal wave
C) it's not a wave at all
Answer: Transverse
CTWaves-3.
The graph below shows a snapshot of a wave on a string which is traveling to the right. There is
a bit of paint on the string at point P.
y
vwave
P
x
At the instant shown, the velocity of paint point P has which direction?
Answer: downward
A
B
D
C
E) None of these
At the instant shown, the acceleration of the particle has which direction? (Same choices)
Answer: downward
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CTWaves-4. Three waves are traveling along identical strings (same mass per length, same
tension, same everything). Wave B has twice the amplitude of the other two. Wave C has 1/2
the wavelength than A or B.
Which Wave goes slowest? A
B
C
D) All have same v
Answer: All have same v
vwave
y
A
x
y
B
x
y
C
x
Which wave has the highest frequency?
A
B
C
D) All 3 have the same frequency
Answer: C
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CTWaves-5. Consider the equation x – v t = , where v and  are constants. The variable x is
position and t is the time. A point x that obeys this equation is a point that
A)
B)
C)
D)
E)
increases (moves to the right) with speed v
decreases (moves to the left) with speed v
is constant x (not moving)
increases (moves to the right) with speed 
decreases (moves to the left) with speed 
x
Answer: increases (moves to the right) with speed v
CTWaves-6. Two traveling waves 1 and 2 are described by the equations.
y1 (x, t)  2sin(2x  t)
y 2 (x, t)  4sin(x  0.8 t)
All the numbers are in the appropriate SI (mks) units.
Which wave has the higher speed?
A) 1
B) 2
C) Both have the same speed.
The wavelength  of wave 1 is most nearly
A) 1m
B) 2m
C) 3m
D) 4m
The period of wave 1 is most nearly
A) 1s
B) 2 s
C) 3 s
D) 6 s
Answers: Wave 2 has the higher speed. The speed of wave 1 is ½. The speed of wave 2 is 0.8.
The wavelength of wave 1 is about 3 m ( m, to be exact). The period of wave 1 is about 6 s
(2 s, to be exact)
y(x, t)  Asin( k x   t ) ,
where amplitude A, wave number k  2 /  and angular frequency  2 / T are constants.
CTWaves-7. A 1D sinusoidal traveling wave is given by
If we take the derivative
dy
while holding x constant , (called the partial derivative  y ), then
dt
t
the magnitude d y is
dt
A) the speed of the wave
B) something else
Answer: Something else. |dy/dt| gives the transverse speed of the atoms in the string at a
particularly value of x. This is completely different than the speed of the wave, which is the
speed of a particular “hump” in the sinusoidal shape.
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CTWaves-8. Two impulse waves are approaching each other, as shown. Which picture correctly
shows the total wave when the two waves are passing through each other?
A)
B)
C)
D)
Answer: D
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CTWaves-9. When you turn up the volume on your sound system, ..
A) the speaker cone oscillates back and forth more rapidly, completing more cycles per second
B) the speaker cone oscillates back and forth more slowly, completing fewer cycles per second
C) the speaker cones oscillates back and forth a farther distance in each cycle
D) the speaker cones oscillates back and forth a shorter distance in each cycle
E) None of these
Answer: C
CTWaves-10. A string is clamped at both ends and then plucked so that it vibrates in a standing
wave mode between two extreme positions A and C. Let upward motion correspond to positive
velocities. When the string is in position B, the instantaneous velocity of points along the string
is...
A) zero everywhere.
B) positive everywhere.
C) negative everywhere.
D) depends on the position.
Answer: depends on the position
+
A
B
C
When the string is in position C, the instantaneous velocity of points along the string is... (same
choices)
Answer: zero everywhere.
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CTWaves-11. Three pressure waves in air (sound waves) , all with the mathematical form
  x t 
y(x, t)  A sin 2     , are labeled A, B, and C. Which sound is the loudest and which is
   T 
the highest pitch?
y
A
x
y
B
x
y
C
x
Answer: B is loudest (highest amplitude) and C is highest pitch (highest frequency, shortest
wavelength).
CTWaves-12. Inhaling helium gas makes your voice higher-pitched. From this observation, you
can deduce what about the speed of sound in helium gas compared to that in air?
A)
Nothing at all
B)
The speed of sound in He in faster than in air
C)
The speed of sound in He is slower than in air
Answer: The speed of sound in He in faster than in air
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CTWaves-13. Vectors

A

and B are any two non-zero vectors. The
angle between the vectors is . What is the angle between
 

B  A and B ?
A) 0
B) 
A
o
C) 90
D) 180
o

B
E) Question makes no sense
Answer: 90o
B×A
A

B