Transcript A woman who weighs 500 N is standing on a board that

A woman who weighs 500 N is standing on a board that weighs
100 N. The board is supported at each end, and the support force
at the right end is 3 times bigger than the support force at the left
end. If the board is 8 m long, how far from the right end is the
woman standing?
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4.0 m
2.0 m
2.7 m
1.6 m
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An automobile accelerates from zero to 30 m/s
in 6 s. The wheels have a diameter of 0.4 m.
What is the angular acceleration of each wheel?
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5 rad/s2
15 rad/s2
25 rad/s2
35 rad/s2
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A bus is designed to draw its power from a rotating flywheel that is
brought up to its maximum speed (3000 rpm) by an electric motor.
The flywheel is a solid cylinder of mass 1000 kg and diameter 1 m
(Icylinder = 1/2 MR3). If the bus requires an average power of 10
kilowatts, how long will the flywheel rotate?
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308 s
617 s
925 s
1234 s
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An 800 N billboard worker stands on a 4 m scaffold weighing 500 N
and supported by vertical ropes at each end. How far would the
worker stand from one of the supporting ropes to produce a tension
of 550 N in that rope?
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1.4 m
2.0 m
2.5 m
2.7 m
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An 80 kg man is one-fourth of the way up a 10 m ladder that
is resting against a smooth, frictionless wall. If the ladder is
20 kg and it makes an angle of 60° with the ground, find the
force of friction of the ground on the foot of the ladder.
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784 N
196 N
50 N
138 N
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A 100 N uniform ladder of length 8 m rests against a smooth
vertical wall. If the coefficient of static friction between ladder
and floor is 0.40, what is the maximum angle that the ladder
can make with the floor before it slips?
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22°
51°
18°
42°
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A meter stick is supported by a knife edge at the 50 cm mark
and has masses of 0.40 and 0.60 kg hanging from the 20 cm
and 80 cm marks, respectively. Where should a third mass of
0.30 kg be hung to keep the stick balanced?
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20 cm
70 cm
30 cm
25 cm
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An 800 N billboard worker stands on a 4 m scaffold
supported by vertical ropes at each end. If the scaffold
weighs 500 N and the worker stands 1 m from one end,
what is the tension in the rope nearest the worker?
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450 N
500 N
800 N
850 N
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A 20 kg child wants to use a 10 kg board that is 4.0 m long as a
seesaw. Since all her friends are busy, she decides to seesaw by
herself by putting the support at the center of gravity when she sits
on one end of the board. How far from her will the support point
be?
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2.0 m
1.0 m
0.67 m
0.33 m
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An astronaut is on a 100 m life-line outside a spaceship,
circling the ship with an angular velocity of 0.1 rad/s.
How far can she be pulled in before the centripetal
acceleration reaches 5g = 49 m/s2 ?
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10.1 m
50.0 m
72.7 m
89.9 m
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A heavy bank vault door is opened by the application of
a force of 300 N directed perpendicular to the plane of
the door and 0.8 m from the hinges. What is the torque
due to this force about an axis through the hinges?
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120 N-m
240 N-m
300 N-m
360 N-m
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A uniform bridge span weighs 50 x 103 N and is 40.0 m long.
An automobile weighing 15 x 103 N is parked with its center
of gravity located 12.0 m from the right pier. What upward
support force is provided by the left pier?
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29.5 x 103 N
35.5 x 103 N
65.0 x 103 N
32.5 x 103 N
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Two hoops or rings (I = MR2) are centered, lying on a phonograph
record. The smaller one has a radius of .05 m and the larger a
radius of 0.1 m. Both have a mass of 3 kg. What is the total
moment of inertia as the record turns around? Ignore the mass of
the record.
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0.030 kg-m2
0.0075 kg-m 2
0.0375 kg-m 2
0.075 kg-m 2
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If a long rod of length L is hinged at one end, the moment of inertia
as the rod rotates around that hinge is ML2/3. A 2 m rod with a
mass of 3 kg is hinged at one end, is held in a horizontal position,
and then released as the free end is allowed to fall. What is the
angular acceleration as it is released?
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3.70 rad/s2
7.35 rad/s2
2.45 rad/s2
4.90 rad/s2
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A meter stick is hinged at its lower end and allowed to
fall from a vertical position. If its moment of inertia is
ML2/3, with what angular velocity does it hit the table?
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5.42 radians/s
2.71 radians/s
1.22 radians/s
0.61 radians/s
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A 40 kg boy is standing on the edge of a stationary 30
kg platform that is free to rotate. The boy tries to walk
around the platform in a counterclockwise direction. As
he does
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the platform doesn't rotate.
the platform rotates in a clockwise
direction just fast enough so that
the boy remains stationary relative
to the ground.
the platform rotates in a clockwise
direction while the boy goes
around in a counterclockwise
direction relative to the ground.
both go around with equal angular
velocities but in opposite
directions.
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A grinding wheel with a moment of inertia of 2.0 kg-m2
has a 2.5 N-m torque applied to it. What is its final
kinetic energy 10 seconds after starting from rest?
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312 J
237 J
156 J
106 J
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A phonograph record and turntable combination have a
moment of inertia of 3.0 x 10-4 kg-m2 and rotate with an
angular velocity of 3.5 rad/sec. What net torque must be
applied to bring the system to rest within 3 s?
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4.5 x 10-3 N-m
7.5 x 10-4 N-m
3.5 x 10-4 N-m
5.0 x 10-4 N-m
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A figure skater with arms initially extended starts
spinning on the ice at 3 rad/s. After she then pulls her
arms into her body, which of the following results?
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a smaller rotational rate
a greater rotational rate
a greater angular
momentum
a smaller angular
momentum
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A grinding wheel with a moment of inertia of 2.0 kg-m2
is initially at rest. What angular momentum will it have
10 s after a 2.5 N-m torque is applied to it?
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25.0 kg-m2 /s
7.5 kg-m2 /s
4.0 kg-m2 /s
0.25 kg-m2 /s
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The quantity, moment of inertia, in terms of the
fundamental quantities (mass, length, time) is
equivalent to which of the following?
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ML2T-2
ML
ML2
ML-1T-2
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The quantity, angular momentum, in terms of
the fundamental quantities (mass, length, time)
is equivalent to which of the following?
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MLT-2
ML2T-1
ML2T-3
ML3T-4
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If a net torque is applied to an object, that
object will experience which of the
following?
1. a constant angular
velocity
2. an angular
acceleration
3. a constant moment of
inertia
4. an increasing moment
of inertia
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According to Newton's second law, the angular
acceleration experienced by an object is directly
proportional to which of the following?
1. its moment of inertia
2. the net applied torque
3. both the object's size
and its moment of
inertia
4. the object's size
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A grinding wheel with a moment of inertia of 2.0 kg-m2
has a net torque of 2.5 N-m applied to it. What angular
acceleration does it experience?
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5.0 rad/sec2
2.0 rad/sec2
1.25 rad/sec2
0.2 rad/sec2
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The Earth's gravity exerts no torque on a satellite orbiting the
Earth in an elliptical orbit. Compare the motion at the point
nearest the Earth (perigee) to the motion at the point farthest
from the Earth (apogee). At these two points
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4.
the tangential velocities
are the same.
the angular velocities are
the same.
the angular momentum is
the same.
the kinetic energies are
the same.
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The Earth's gravity exerts no torque on a satellite orbiting the Earth
in an elliptical orbit. Compare the motion at the point nearest the
Earth (perigee) to the motion at the point farthest from the Earth
(apogee). At the point closest to the Earth
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3.
4.
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the angular velocity will be
greatest although the linear
speed will be the same.
the speed will be greatest
although the angular velocity
will be the same.
the kinetic energy and angular
momentum will both be greater.
none of these.
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A solid cylinder (I = MR2/2) has a string wrapped around it many
times. When I release the cylinder, holding on to the string, the
cylinder falls and spins as the string unwinds. What is the
downward acceleration of the cylinder as it falls?
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0
4.9 m/s2
6.5 m/s2
9.8 m/s2
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An astronaut is on a 200 m life-line circling the
spaceship at two rev. per min. The line is shortened until
his speed reaches 50 m/s. How long is the life-line at
that time?
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4.
8m
50 m
141 m
168 m
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A majorette takes two batons and fastens them together in the
middle at right angles to make an "x" shape. Each baton was 0.8 m
long and each ball on the end is 0.20 kg. (Ignore the mass of the
rods.) What is the moment of inertia if the arrangement is spun
around an axis through the center perpendicular to both rods?
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0.064 kg-m2
0.096 kg-m2
0.128 kg-m2
0.320 kg-m2
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9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
What must be an angular velocity of a cylinder (I = MR2/2) rolling on
the ground at the bottom of a hill so that it will be able to roll to the
top of the hill if the hill is 10 m long and 3 m high? The mass of the
cylinder is 2 kg and the radius is 0.4 m.
25% 25% 25% 25%
1.
2.
3.
4.
15.7 rad/s
27.1 rad/s
19.2 rad/s
28.6 rad/s
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A majorette takes two batons and fastens them together in the
middle at right angles to make an "x" shape. Each baton was 0.8 m
long and each ball on the end is 0.20 kg. (Ignore the mass of the
rods.) What is the moment of inertia if the arrangement is spun
around an axis formed by one of the batons?
25% 25% 25% 25%
1.
2.
3.
4.
0.048 kg-m2
0.064 kg-m2
0.192 kg-m2
0.320 kg-m2
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A rotating flywheel can be used as a method to store energy. If it
has 10 x 105 J of kinetic energy when rotating at 400 rad/s, and if a
frictional torque of 4.0 N-m acts on the system, in what interval of
time would the flywheel come to rest?
25% 25% 25% 25%
1.
2.
3.
4.
3.5 min
7.0 min
14 min
21 min
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
An initially installed flywheel can store 106 J of kinetic energy when rotating
at 300 rad/s. It is replaced by another flywheel of the same size but made
of a lighter and stronger material. If its mass is half that of the original and
it is now capable of achieving a rotational velocity of 600 rad/s, what
maximum energy can be stored?
25% 25% 25% 25%
1.
2.
3.
4.
40 x 105 J
20 x 105 J
10 x 105 J
5.0 x 105 J
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A rotating flywheel can be used as a method to store
energy. If it is required that such a device be able to
store up to a maximum of 10 x 105 J when rotating at
400 rad/s, what moment of inertia is required?
25% 25% 25% 25%
1.
2.
3.
4.
50 kg-m2
25 kg-m2
12.5 kg-m2
6.3 kg-m2
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A phonograph turntable has a moment of inertia of 2.5 x 10-2 kg-m2 and
spins freely on a frictionless bearing at 33.3 rev/min. A 0.25 kg ball of putty
is dropped vertically on the turntable and sticks at a point 0.20 m from the
center. By what factor does the kinetic energy of the system change after
the putty is dropped onto the turntable?
25% 25% 25% 25%
1.
2.
3.
4.
0.71
1.00
0.82
1.50
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A cylinder with its mass concentrated toward the center has a
moment of inertia of 0.1 MR2. If this cylinder is rolling without
slipping along a level surface with a linear velocity v, what is the
ratio of its rotational kinetic energy to its linear kinetic energy?
25% 25% 25% 25%
1.
2.
3.
4.
1/10
1/5
1/2
1/1
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A solid sphere with mass, M, and radius, R, rolls along a
level surface without slipping with a linear velocity, v.
What is the ratio of rotational to linear kinetic energy?
(For a solid sphere, I = 0.4 MR2)
25% 25% 25% 25%
1.
2.
3.
4.
1/4
1/2
1/1
2/5
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A phonograph turntable has a moment of inertia of 2.5 x 10-2 kg-m2 and
spins freely on a frictionless bearing at 33.3 rev/min. A 0.25 kg ball of putty
is dropped vertically on the turntable and sticks at a point 0.20 m from the
center. By what factor does the angular momentum of the system change
after the putty is dropped onto the turntable?
25% 25% 25% 25%
1.
2.
3.
4.
1.22
1.00
0.82
1.50
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A figure skater on ice with arms extended, spins at a
rate of 2.0 rev/s. After she draws her arms in, she spins
at 5 rev/s. By what factor does her moment of inertia
change in the process?
25% 25% 25% 25%
1.
2.
3.
4.
2.5
3.0
0.4
0.2
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A figure skater on ice with arms extended, spins at a
rate of 2.0 rev/s. After she draws her arms in, she spins
at 5 rev/s. By what factor does the skater's kinetic
energy change when she draws her arms in?
25% 25% 25% 25%
1.
2.
3.
4.
2.5
3.0
0.4
0.2
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A gyroscope has a moment of inertia of 0.14 kg-m2 and has an
initial angular velocity of 15 rad/s. If a lubricant is applied to the
bearings of the gyroscope so that frictional torque is reduced to 2.0
x 10-2 N-m, then in what time interval will the gyroscope coast from
15 rad/s to zero?
25% 25% 25% 25%
1.
2.
3.
4.
150 s
105 s
90 s
180 s
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A phonograph turntable has a moment of inertia of 2.5 x 10-2 kg-m2
and spins freely on a frictionless bearing at 33.3 rev/min. A 0.25 kg
ball of putty is dropped vertically on the turntable and sticks at a
point 0.20 m from the center. What is the new rate of rotation of the
system?
25% 25% 25% 25%
1.
2.
3.
4.
40.8 rev/min
23.8 rev/min
33.3 rev/min
27.2 rev/min
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A solid cylinder with a mass of 3.0 kg and radius of 0.2 m, starts
from rest at the top of a ramp, inclined at 15°, and rolls to the
bottom without slipping. (For a cylinder I = 0.5MR2) The upper end
of the ramp is 1.2 m higher than the lower end. What would the
linear velocity of the cylinder be at the bottom? (g = 9.8 m/s2)
25% 25% 25% 25%
1.
2.
3.
4.
4.7 m/s
4.3 m/s
4.0 m/s
2.4 m/s
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A gyroscope has a moment of inertia of 0.14 kg-m2 and
has an initial angular velocity of 15 rad/s. Friction in the
bearings causes its velocity to reduce to zero in 30 s.
What is the value of the frictional torque?
25% 25% 25% 25%
1.
2.
3.
4.
3.3 x 10-2 N-m
8.1 x 10-2 N-m
14.0 x 10-2 N-m
7.0 x 10-2 N-m
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A solid sphere with a mass of 4.0 kg and radius 0.12 m,
starts from rest at the top of a ramp inclined at 15°, and rolls
to the bottom. The upper end of the ramp is 1.2 m higher
than the lower end. What is the linear velocity of the sphere
when it reaches the bottom of the ramp? (Note: I = 0.4MR2
for a solid sphere and g = 9.8 m/s2) 25% 25% 25% 25%
1.
2.
3.
4.
4.7 m/s
4.1 m/s
3.4 m/s
2.4 m/s
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A bucket filled with water has a mass of 23 kg and is attached to a rope
which in turn is wound around a 0.05 m radius cylinder, with crank, at the
top of a well. The moment of inertia of the cylinder and crank is 0.12 kg-m2.
The bucket and water are first raised to the top of the well and then
released to fall back into the well. What is the kinetic energy of the cylinder
and crank at the instant the bucket is moving with a speed of 7.9 m/s?
25% 25% 25% 25%
1.
2.
3.
4.
2.1 x 103 J
1.5 x 103 J
0.7 x 103 J
0.4 x 103 J
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A solid sphere with a mass of 4.0 kg and radius 0.12 m, starts from
rest at the top of a ramp inclined at 15°, and rolls to the bottom. The
upper end of the ramp is 1.2 m higher than the lower end. What is
the total kinetic energy of the sphere when it reaches the bottom?
(g = 9.8 m/s2 and assume that it rolls without slipping.)
25% 25% 25% 25%
1.
2.
3.
4.
70.0 J
47.0 J
18.0 J
8.8 J
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A bucket filled with water has a mass of 23 kg and is attached to a rope
which in turn is wound around a 0.05 m radius cylinder at the top of a well.
The bucket and water are first raised to the top of the well and then
released. The bucket and water are moving with a speed of 7.9 m/s upon
hitting the water surface in the well below. What is the angular velocity of
the cylinder at this instant?
25% 25% 25% 25%
1.
2.
3.
4.
39 rad/s
79 rad/s
118 rad/s
158 rad/s
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A uniform, horizontal beam of length 6 m and weight 120 N is attached at
one end to a wall by a pin connection (so that it may rotate). The opposite
end is supported by a cable attached to the wall above the 3 pin. The cable
makes an angle of 60° with the horizontal. What is the tension in the cable
needed to maintain the beam in equilibrium?
25% 25% 25% 25%
1.
2.
3.
4.
35 N
69 N
60 N
120 N
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A bucket filled with water has a mass of 23 kg and is attached to a
rope which in turn is wound around a 0.05 m radius cylinder at the
top of a well. A crank with a turning radius of 0.25 m is attached to
the end of the cylinder. What minimum force directed perpendicular
to the crank handle is required to raise the bucket and water?
(Assume the rope's mass is negligible, that cylinder turns on
frictionless bearings, and that g = 9.8 m/s225%
)
25% 25% 25%
1.
2.
3.
4.
45 N
68 N
90 N
135 N
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A bucket filled with water has a mass of 23 kg and is attached to a rope which in
turn is wound around a 0.05 m radius cylinder at the top of a well. A crank with a
turning radius of 0.25 m is attached to the end of the cylinder and the moment of
inertia of cylinder and crank is 0.12 kg-m2. If the bucket and water are first raised to
the top of the well and then released, what is the acceleration of bucket and water
as they fall toward the bottom of the well? (Assume rope's mass is negligible, that
cylinder turns on frictionless bearings and that g = 9.8 m/s2)
25% 25% 25% 25%
1.
2.
3.
4.
4.7 m/s2
6.3 m/s2
7.4 m/s2
9.8 m/s2
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A bucket filled with water has a mass of 23 kg and is attached to a
rope which in turn is wound around a 0.05 m radius cylinder at the
top of a well. What torque does the weight of water and bucket
produce on the cylinder? (g = 9.8 m/s2)
25% 25% 25% 25%
1.
2.
3.
4.
33.7 N-m
17.0 N-m
11.3 N-m
22.6 N-m
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A baseball pitcher, loosening up his arm before a game, tosses a
0.15 kg ball using only the rotation of his forearm, 0.32 m in length
to accelerate the ball. What is the moment of inertia of the ball
alone, as it moves in a circular arc with a 0.32 meter radius?
25% 25% 25% 25%
1.
2.
3.
4.
1.5 x 10-2 kg-m2
16 x 10-2 kg-m2
4.0 x 10-2 kg-m2
7.6 x 10-2 kg-m2
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A baseball pitcher, loosening up his arm before a game, tosses a 0.15 kg
ball using only the rotation of his forearm, 0.32 m in length, to accelerate
the ball. If the ball starts at rest and is released with a speed of 12 m/s in a
time of 0.4 s, what torque is applied to the ball while being held by the
pitcher's hand to produce the angular acceleration?
25% 25% 25% 25%
1.
2.
3.
4.
1.1 N-m
10.8 N-m
7.2 N-m
1.44 N-m
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A baseball pitcher, loosening up his arm before a game, tosses a
0.15 kg ball using only the rotation of his forearm, 0.32 m in length,
to accelerate the ball. If the ball starts at rest and is released with a
speed of 12 m/s in a time of 0.4 s, what is the average angular
acceleration of the arm and ball?
25% 25% 25% 25%
1.
2.
3.
4.
0.067 rad/sec2
94 rad/sec2
15 rad/sec2
37 rad/sec2
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
The Earth moves about the Sun in an elliptical orbit. As
the Earth moves closer to the Sun, then which of the
following best describes the Earth-Sun system's
moment of inertia?
25% 25% 25% 25%
1.
2.
3.
4.
decreases
increases
remains constant
None of these
choices are valid
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
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A bowling ball has a mass of 7.0 kg, a moment of inertia
of 2.8 x 10-2 kg-m2 and a radius of 0.10 m. If it rolls
down the lane without slipping at a linear speed of 4.0
m/s, what is its angular velocity?
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2.
3.
4.
0.8 rad/s
10.0 rad/s
0.05 rad/s
40.0 rad/s
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A bowling ball has a mass of 7.0 kg, a moment of inertia
of 2.8 x 10-2 kg-m2 and a radius of 0.10 m. If it rolls
down the lane without slipping at a linear speed of 4.0
m/s, what is its total kinetic energy?
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1.
2.
3.
4.
44.8 J
32.0 J
11.2 J
78.4 J
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The total kinetic energy of a baseball
thrown with a spinning motion is a
function of which of the following?
1. its linear velocity but
not rotational velocity
2. its rotational velocity
but not linear velocity
3. both linear and
rotational velocities
4. neither linear nor
rotational velocity
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