louey (cal2859) – Ch4HW4 – florin – (56930)
1
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printout
should
have
24
questions.
Multiplechoice questions may continue on
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before answering.
001(part1of2)10.0points
If an object is moving with constant momen
tum
vectorp
=
(
12
,
−
12
,
−
10
)
kg
·
m
/
s
,
what is the magnitude of the rate of change of
momentum
dvectorp
dt
?
Correct answer: 0 kg
·
m
/
s.
Explanation:
A
constant
momentum implies that the rate
of change of momentum is zero.
002(part2of2)10.0points
What is the magnitude of the net force acting
on the object?
Correct answer: 0 N.
Explanation:
By the Momentum Principle,
Δ
vectorp
=
vector
F
net
Δ
t,
if the rate of change of momentum is zero,
then the net force is also zero.
003(part1of4)10.0points
A ball whose mass is 1
.
3 kg is suspended from
a spring whose stiffness is 3 N
/
m.
The ball
oscillates up and down with an amplitude of
14 cm. Take
g
= 9
.
8 m
/
s
2
.
What is the angular frequency
ω
?
Correct answer: 1
.
51911 rad
/
s.
Explanation:
The angular frequency is given by
ω
=
radicalbigg
k
m
=
radicalBigg
3 N
/
m
1
.
3 kg
=
1
.
51911 rad
/
s
.
004(part2of4)10.0points
What is the frequency?
Correct answer: 0
.
241774 s

1
.
Explanation:
The frequency is given by
f
=
ω
2
π
=
0
.
241774 s

1
.
005(part3of4)10.0points
What is the period?
Correct answer: 4
.
1361 s.
Explanation:
The period is given by
T
=
1
f
=
1
0
.
241774 s

1
=
4
.
1361 s
.
006(part4of4)10.0points
Suppose this apparatus was taken to the
Moon, where the strength of the gravitational
field is only 1/6 of that on Earth. What would
the period be on the Moon? (Consider care
fully how the period depends on properties of
the system; look at the equation.)
Correct answer: 4
.
1361 s.
Explanation:
This period is the same as the period you
found in part 3, since
g
does not enter the
formula for
T
.
007
10.0points
A mass of 6 kg is connected to a horizon
tal spring whose stiffness is 18 N
/
m.
When
the spring is relaxed,
x
= 0.
The spring is
stretched so that the initial value of
x
= 0
.
3 m.
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 Spring '08
 Turner
 Atom, Mass, Correct Answer, tnew

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