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Question 1, chap 15, sect 1.
part 1 of 3
10 points
A weight suspended from a spring is seen
to bob up and down over a distance of 15 cm
twice each second.
What is its frequency?
Correct answer: 2 Hz (tolerance
±
1 %).
Explanation:
freq =
2 bobs
1 second
=
2 Hz
.
Question 2, chap 15, sect 1.
part 2 of 3
10 points
What is its period?
Correct answer: 0
.
5 s (tolerance
±
1 %).
Explanation:
period =
1
freq
=
1
2 Hz
=
0
.
5 s
.
Question 3, chap 15, sect 1.
part 3 of 3
10 points
What is its amplitude?
Correct answer: 7
.
5 cm (tolerance
±
1 %).
Explanation:
The amplitude is the distance from the
equilibrium position to maximum displace
ment:
1
2
(15 cm) =
7
.
5 cm
.
Question 4, chap 15, sect 1.
part 1 of 1
10 points
A particle hangs from a spring and os
cillates with a period of 0
.
37 s.
How
much will the spring, at rest, shorten
from the equilibrium position with the par
ticle hung,
if the particle is removed?
With Particle
Without Particle
1.
0
.
271869 m
2.
0
.
0679673 m
3.
0
.
543738 m
4.
0
.
106763 m
5.
0
.
135935 m
6.
0
.
0339836 m
correct
Explanation:
When the particle hangs and oscillates on
the spring, we have
T
= 2
π
r
m
k
, where
T
is the oscillation period of the spring with
particle hung,
m
is the mass of the particle,
and
k
is the spring constant. So,
k
=
4
π
2
m
T
2
.
At equilibrium with the particle hung, the
spring is stretched for
x
=
mg
k
.
Put the
expression of
k
into this equation and get
x
=
gT
2
4
π
2
= 0
.
0339836 m
Question 5, chap 15, sect 1.
part 1 of 1
10 points
Given:
The oscillation of a massspring
system
x
=
x
m
cos(
ω t
+
φ
)
,
where
x
m
is a positive number.
At time
t
= 0, the mass is at the equilibrium
point
x
= 0 and it is moving with positive
velocity
v
0
.
What is the phase angle
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 Spring '09
 KLEINMAN
 Physics, Work

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