homework 23 – BAUTISTA, ALDO – Due: Mar 27 2006, 4:00 am
1
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Question 1
Part 1 of 3.
10 points.
An air puck of mass 0
.
353 kg is tied to
a string and allowed to revolve in a circle
of radius 0
.
55 m on a horizontal, frictionless
table.
The other end of the string passes
through a hole in the center of the table and
a mass of 1
.
3 kg is tied to it. The suspended
mass remains in equilibrium while the puck
revolves.
The acceleration of gravity is 9
.
8 m
/
s
2
.
0
.
55 m
v
1
.
3 kg
0
.
353 kg
What is the tension in the string?
Correct answer: 12
.
74 N (tolerance
±
1 %).
Explanation:
r
v
Mg
m
Since the suspended mass is in equilibrium,
the tension is
T
=
M g
= (1
.
3 kg)
(
9
.
8 m
/
s
2
)
=
12
.
74 N
.
Question 2
Part 2 of 3.
10 points.
What is the horizontal force acting on the
puck?
Correct answer: 12
.
74 N (tolerance
±
1 %).
Explanation:
The horizontal force acting on the puck is
the tension in the string, so
F
c
=
T
=
12
.
74 N
.
Question 3
Part 3 of 3.
10 points.
What is the speed of the puck?
Correct answer: 4
.
45532
m
/
s (tolerance
±
1
%).
Explanation:
F
c
=
m v
2
r
v
=
r
F
c
r
m
=
s
(12
.
74 N) (0
.
55 m)
0
.
353 kg
=
4
.
45532 m
/
s
.
Question 4
Part 1 of 1.
10 points.
A wheel rotates with a constant angular
acceleration of 4
.
53 rad
/
s
2
.
Suppose that at
t
0
= 0, the angular speed of the wheel is
1
.
39 rad
/
s.
What angle does the wheel rotate through
in 3
.
5 s?
Correct answer: 5
.
19024
rev (tolerance
±
1
%).
Explanation:
For the angle of rotation of the wheel (for a
constant angular acceleration) we have
θ

θ
0
=
ω
0
t
+
1
2
α t
2
= (1
.
39 rad
/
s ) (3
.
5 s )
+
1
2
(4
.
53 rad
/
s
2
) (3
.
5 s )
2
= 32
.
6112 rad = 5
.
19024 rev
.
Question 5
Part 1 of 3.
10 points.
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View Full Documenthomework 23 – BAUTISTA, ALDO – Due: Mar 27 2006, 4:00 am
2
A 4
.
7 kg mass is connected by a light cord to
a 3
.
3 kg mass on a smooth surface as shown.
The pulley rotates about a frictionless axle
and has a moment of inertia of 0
.
73 kg
·
m
2
and a radius of 0
.
58 m.
The acceleration of gravity is 9
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 Spring '08
 Turner
 Force, Friction, Mass, Work, Velocity, Correct Answer

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