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portillo (gdp347) – oldhomework 37 – Turner – (58185)
1
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beFore answering.
001
10.0 points
Radio waves travel at the speed oF light:
3
×
10
5
km
/
s.
What is the wavelength oF radio waves re
ceived at 90
.
5 MHz on your ±M radio dial?
Correct answer: 3
.
31492 m.
Explanation:
Let :
v
= 3
×
10
5
km
/
s
= 300 million m
/
s
and
f
= 90
.
5 MHz
= 90
.
5 million Hz
.
λ
=
v
f
=
300 million m
/
s
90
.
5 million Hz
=
3
.
31492 m
.
002
10.0 points
Two harmonic waves are described by
y
1
=
A
sin(
k x

ω t

φ
1
)
and
y
2
=
A
sin(
k x

ω t

φ
2
)
,
where
k
= 6 m

1
,
A
= 8 m
, ω
= 641 rad
/
s
,
φ
1
= 0 rad
,
and
φ
2
= 2 rad
.
What is the Frequency oF the resultant wave
y
=
y
1
+
y
2
?
Correct answer: 102
.
018 Hz.
Explanation:
Since
sin
θ
1
+ sin
θ
2
= sin
θ
1
+
θ
2
2
cos
θ
1

θ
2
2
,
the resultant wave is
y
=
y
1
+
y
2
=
A
cos
p
φ
2

φ
1
2
P
×
sin
p
k x

ω t

φ
1
+
φ
2
2
P
and the Frequency is
f
=
ω
2
π
=
641 rad
/
s
2
π
=
102
.
018 Hz
.
003
(part 1 oF 2) 10.0 points
A harmonic wave in a wire has amplitude
2
.
16 mm, wavelength 2
.
3 m, and Frequency
790 Hz.
What is the propagation speed oF the
wave?
Correct answer: 1817 m
/
s.
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This note was uploaded on 01/25/2012 for the course CHEM 302 taught by Professor Mccord during the Spring '10 term at University of Texas at Austin.
 Spring '10
 McCord

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