Notes

Question 1
(1 points)

(#247193) {Angular Velocity}



What is the angular speed of the second hand of a 12-hour clock? Give your answer in units of radians per second.

Image size: SMLMax



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
rad/s
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Question 2
(1 points)

(#437608) {Angular Velocity / Linear Speed}



Earth turns on its axis about once every 24 hours. The Earth's equatorial radius is 6.38 x 106 m. If the Earth were to suddenly stop spinning about its axis, with what speed would Earth's inhabitants who live at the equator will initially "fly away" from their surroundings?

Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

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m/s
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Question 3
This question contains multiple parts. Make sure to read all the instructions and answer each part.

(#882722) {Centripetal Acceleration}



Sarah and Tom are riding on a merry-go-round that is revolving at a constant rate. Sarah is sitting on the outer edge and Tom is half-way in from the edge.

Part a
(1 points)
Consider the following statements about Tom and Sarah's linear speeds (i.e., tangential velocities) and angular velocities?

Which one of the statements is true?



Select the correct answer
Sarah and Tom have the same angular velocity, but Tom has a greater linear speed than Sarah.
Sarah and Tom have the same angular velocity and the same linear speed.
Sarah and Tom have neither the same angular velocity nor the same linear speed.
Sarah and Tom have the same angular velocity, but Sarah has a greater linear speed than Tom.
Sarah and Tom have the same linear speed, but Tom has a greater angular velocity than Sarah.
Sarah and Tom have the same linear speed, but Sarah has a greater angular velocity than Tom.
No answer submitted
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Part b
(1 points)
What is the relationship between their centripetal accelerations?

Select the correct answer
Sarah experiences a centripetal acceleration that is four-times that of Tom's.
Tom experiences a centripetal acceleration that is twice that of Sarah's.
Tom experiences a centripetal acceleration that is eight-times that of Sarah's.
Sarah experiences a centripetal acceleration that is twice that of Tom's.
They are the They experience the same centripetal acceleration.
Tom experiences a centripetal acceleration that is four-times that of Sarah's.
No answer submitted
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Question 4
(1 points)

(#576822) {Centripetal Acceleration}



A centrifuge is a rotating device in which objects are placed a certain radial distance from the center of rotation and spun at high speeds so that they experience centripetal acceleration. Astronauts are spun in a giant centrifuge as a physical test before they fly in space. With what linear speed would an astronaut need to be spinning in order to experience a centripetal acceleration of 3 g's at a radius of 10.3 m? (1 g = 9.80 m/s
2
​2
​​ ).





Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

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m/s
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Question 5
(1 points)

(#076824) {Angular Acceleration}



The figure below shows a graph of the angular velocity of a stereo turntable as it is turned on to play a vinyl LP album. The angular velocity is plotted in revolutions-per-minute (rpm). What is the angular acceleration of the turntable at t = 0.5 seconds on the graph? (Give your answer in units of rad/s2)



Image size: SMLMax



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here

r
a
d
/
s
2
rad/s
​2
​​
No answer submitted
0 of 5 checks used

Question 6
This question contains multiple parts. Make sure to read all the instructions and answer each part.


(#602437) {Rotational Kinematics}



The hammer throw event in track and field involves spinning a heavy ball attached to a strong wire in a circle, then releasing it at just a particular moment in the throw, and at the particular angle, attempting to maximize the horizontal range of its trajectory away from the starting point.

Image size: SMLMax



Part a
(1 points)
At the moment that the hammer thrower shown above is spinning at an angular rate of 3.88 revolutions per second, with the ball located 1.02 m from the center axis of the spin, what is the tangential velocity of ball?

Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

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m/s
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Part b
(1 points)
When the athlete releases her ball, she is aiming to maximize the distance from the starting ring. Assume she releases the ball at an angle of 47.4 degrees above horizontal, and the ball travels a total horizontal distance of 29.8 m. What angular velocity must she have achieved (in radians/s) at the moment of the throw, assuming the ball is 1.02 m from the axis of rotation during the spin?



[For this calculation, you may assume that hammer is released from ground level - treating the small actual release height as negligible relative to the distances involved in this problem]

Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

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radians /second
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Question 7
(1 points)

(#710921) {Multi-concept}




A tabletop micro-centrifuge spins at 6000 rpm (revolutions per minute). When the lid is opened, the automatic shut-off circuit kicks in and the micro-centrifuge begins to slow down with a constant angular deceleration. In the first 10.0 seconds immediately after the shut-off, it the micro-centrifuge completes 797 full revolutions. Calculate the angular acceleration rate of the slowing micro-centrifuge in units of rad/s2. (Report your answer as a negative number to reflect the fact that the device is actually decelerating)

Image size: SMLMax



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
r
a
d
/
s
2
rad/s
​2
​​
No answer submitted
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Question 8
(1 points)

(#742239) {Multi-concept}




[You should definitely attempt this CHALLENGE question - but it will be counted as a BONUS QUESTION - it will not count against you if you miss it, but will add to your score if you get it correct!]



An electric bike (e-bike) is initially at rest at the start of a long, straight, horizontal bike path. The electric drive on an e-bike imparts a constant angular acceleration of 5.79 rad/s2 to the e-bike's 350-mm radius rear wheel until the e-bike has traveled 3.79 meters. Assume that the wheel rolls along the ground without slipping. Calculate the centripetal acceleration experienced by a point on the outer edge of the wheel when the drive shuts off (at the 3.79-meter point).



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
m
/
s
2
m/s
​2
​​
No answer submitted
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Question 9
(1 points)

(#837745) {Newton’s 2nd Law}



Which of the following objects is in a state of (translational) equilibrium?



(i) an object with zero net force acting on it.

(ii) an object that is static (not moving, and remains that way).

(iii) an object that is moving at a constant speed in a straight line.



Select the correct answer
only (i) and (ii)
all of them
none of them
only (ii)
only (i) and (iii)
only (i)
No answer submitted
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Question 10
(1 points)

(#535653-06) {Newton’s 2nd Law}



A 62.8-kg sprinter starts a race with an acceleration of
4
.
4
3

m
/
s
2
4.43 m/s
​2
​​ . What is the net external force on him?





Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
N
No answer submitted
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Question 11
(1 points)

(#655341) {Newton's Second Law}



The rocket sled shown below decelerates at a rate of
1
9
6

m
/
s
2
196 m/s
​2
​​ . What magnitude of force is necessary to produce this deceleration? Assume that the rockets on the sled have been turned off. The mass of the system is
2
.
1
0
×
1
0
3

k
g
2.10×10
​3
​​ kg.

Image size: SMLMax



Select the correct answer
4
.
1
2
×
1
0
4

N
4.12×10
​4
​​ N
6
.
1
9
×
1
0
5

N
6.19×10
​5
​​ N
9
.
7
7
×
1
0
4

N
9.77×10
​4
​​ N
7
.
2
8
×
1
0
5

N
7.28×10
​5
​​ N
4
.
1
2
×
1
0
5

N
4.12×10
​5
​​ N
No answer submitted
0 of 3 checks used

Question 12
(1 points)

(#627258) {Newton’s 2nd Law}



If the only forces acting on a 2.0 kg mass are
�
⃗
1
=
2
�
^

N
+
4
�
^

N
​F
​⃗
​​
​1
​​ =2
​i
​^
​​ N+4
​j
​^
​​ N and
�
⃗
2
=
6
�
^

N
+
3
�
^

N
​F
​⃗
​​
​2
​​ =6
​i
​^
​​ N+3
​j
​^
​​ N, what is the magnitude of the acceleration of the particle?



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here

m
/
s
2
m/s
​2
​​
No answer submitted
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Question 13
(1 points)

(#806699) {Newton's Second Law}



In the figure below, force
�
⃗
�
​F
​⃗
​​
​B
​​ has twice the magnitude of force
�
⃗
�
​F
​⃗
​​
​A
​​ . Find the direction in which the particle accelerates in this figure. Give your answer as a positive angle (measured counter-clockwise) from the positive x-axis.

Image size: SMLMax



Select the correct answer
3
2
∘
32
​∘
​​
9
0
∘
90
​∘
​​
2
5
4
∘
254
​∘
​​
7
4
∘
74
​∘
​​
1
3
2
∘
132
​∘
​​
2
7
5
∘
275
​∘
​​
No answer submitted
0 of 3 checks used

Question 14
(1 points)

(#181378) {Newton’s 2nd Law}



Consider the block being moved along a frictionless horizontal surface, as depicted in the figure below. The block is pushed from behind by a horizontal force while simultaneously being pulled by a pulling force direct at an angle,
�
θ above the horizontal. If
�
p
u
s
h
=
�
p
u
l
l
=
5
.
4
7

N
F
​push
​​ =F
​pull
​​ =5.47 N, the mass of the block is
�
=
3
.
1
3

k
g
m=3.13 kg, and the angle of the pulling force is
�
=
3
4
.
2
∘
θ=34.2
​∘
​​ , what is the magnitude,
�
a, of the acceleration for the block shown below? The surface is perfectly frictionless and the block does not leave the surface.

Image size: SMLMax



Select the correct answer
3.53
m
/
s
2
m/s
​2
​​
2.41
m
/
s
2
m/s
​2
​​
1.53
m
/
s
2
m/s
​2
​​
3.19
m
/
s
2
m/s
​2
​​
1.89
m
/
s
2
m/s
​2
​​
No answer submitted
0 of 3 checks used

Question 15
(1 points)

(#156647) {Newton's 3rd Law / Newton's 2nd Law}



Suppose that you're driving to Vegas from San Diego, and suddenly an insect splats on your windshield. Let
�
C
a
r
O
n
B
u
g
F
​CarOnBug
​​ be the magnitude of the force that the car exerts on the bug, and let
�
B
u
g
O
n
C
a
r
F
​BugOnCar
​​ be the magnitude of the force that the bug exerts on the car. Which of the following is true?



Select the correct answer
The car exerts a lesser force on the bug than the bug does on the car; thus the bug accelerates less than the car decelerates due to the interaction.
The car exerts a greater force on the bug than the bug does on the car; but the bug accelerates by the same amount that the car decelerates due to the interaction.
The car exerts a lesser force on the bug than the bug does on the car; thus the bug accelerates more than the car decelerates due to the interaction.
The car exerts an equal force on the bug as the bug does on the car; thus the bug accelerates by the same amount that the car decelerates due to the interaction.
The car exerts a greater force on the bug than the bug does on the car; thus the bug accelerates more than the car decelerates due to the interaction.
The car exerts an equal force on the bug as the bug does on the car; thus the bug accelerates more than the car decelerates due to the interaction.
No answer submitted
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Question 16
(1 points)

(#691444) {Newton's 3rd Law}



If a 1100kg artillery shell is fired from a 100,000kg battleship with an acceleration of
2
0
0
0

m
/
s
2
2000 m/s
​2
​​ , then what is the recoil acceleration of the ship? (For this calculation, neglect the force of the water on the ship)

Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here

m
/
s
2
m/s
​2
​​
No answer submitted
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Question 17
(1 points)

(#394971-30) {Newton's 3rd Law} / {Newton's 2nd Law}



Consider the two adjacent blocks shown in the figure below. A horizontal external force, F, is applied rightward to the small block on the left. The horizontal surface on which the blocks slide is frictionless. If M = 1.0 kg and F = 37.1 N, determine magnitude of the force applied by the larger block onto the smaller block. Report the magnitude as a positive number.

Image size: SMLMax



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
N
No answer submitted
0 of 5 checks used

Question 18
(1 points)

(#581724) {Multi-concept}




[You should definitely attempt this CHALLENGE question - but it will be counted as a BONUS QUESTION - it will not count against you if you miss it, but will add to your score if you get it correct!]



A 0.200-kg hockey puck is sitting, initially at rest, on a frictionless ice rink. A constant force of 1.00 N is applied to the puck for 2.88 seconds, directed towards a frictionless semi-circular tube with a radius of r = 1.69 meters. Calculate the magnitude of the centripetal acceleration experienced by the puck as it moves through the frictionless semi-circular tube.

Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here

m
/
s
2
m/s
​2
​​
No answer submitted
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Question 19
(1 points)

(#363218) {Normal Force}





Consider four situations shown below with four identical boxes each with mass 1.0 kg. In each case there is a 10 N force applied to the box. Rank the magnitude of the normal force,
�
�
F
​N
​​ , exerted by the surface on the box, from the least to the greatest value?
�
�
1
F
​N1
​​ refers to the normal force in situation 1,
�
�
2
F
​N2
​​ refers to the normal force in situation 2, etc.

Image size: SMLMax



Select the correct answer
�
�
3
<
�
�
2
<
�
�
4
<
�
�
1
F
​N3
​​ <F
​N2
​​ <F
​N4
​​ <F
​N1
​​
�
�
4
<
�
�
2
<
�
�
3
<
�
�
1
F
​N4
​​ <F
​N2
​​ <F
​N3
​​ <F
​N1
​​
�
�
2
<
�
�
3
<
�
�
1
<
�
�
4
F
​N2
​​ <F
​N3
​​ <F
​N1
​​ <F
​N4
​​
�
�
1
=
�
�
3
<
�
�
4
<
�
�
2
F
​N1
​​ =F
​N3
​​ <F
​N4
​​ <F
​N2
​​
�
�
1
=
�
�
2
=
�
�
3
=
�
�
4
F
​N1
​​ =F
​N2
​​ =F
​N3
​​ =F
​N4
​​
No answer submitted
0 of 3 checks used

Question 20
(1 points)

(#613662) {Inclined Planes}



A 14.1 kg block is placed at the top of a frictionless inclined plane angled at 45.9 degrees relative to the horizontal. When released (from rest), the block slides down the full 7.53 meter length of the incline. Calculate the acceleration of the block as it slides down the incline. [Start by drawing a free-body diagram for the block.] Note that all the information provided may not be necessary to solve the problem.



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
m
/
s
2
m/s
​2
​​
No answer submitted
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Question 21
(1 points)

(#719208) {Inclined Planes}



A 10.00 kg block is placed at the top of a long frictionless inclined plane angled at 31.0 degrees relative to the horizontal. The block is launched down the slope with an initial speed of 5.00 m/s. Calculate how far the block has moved from its starting point after 4.00 seconds. [Assume that the initial velocity is achieved almost instantaneously, that the inclined plane is longer than the distance traveled, and that you can ignore air resistance]



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
meters
No answer submitted
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Question 22
(1 points)

(489210) {Pressure / Compressive Stress}



Consider a force of 750 N (roughly the weight of an adult human). Over what area (in cm2) would this force need to be applied in order achieve a solid pressure (stress) of 9.19 MPa? (roughly around the ultimate compressive strength of skin) [Recall : 1 MPa = 106 Pa , and 1 Pa = 1 N/m2]

Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
c
m
2
cm
​2
​​
No answer submitted
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Question 23
(1 points)

(#449439) {Tension}



If a truck of mass 2.03e+3 kg on the road beside a frozen lake rescue a car of mass 529 kg that has skid onto the frictionless ice. The truck tows the car with a cable and we assume that the cable is massless, horizontal, and does not stretch). What is the tension in the cable when the first car is accelerating at
2
.
2
3

m
/
s
2
2.23 m/s
​2
​​ ?

Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
N
No answer submitted
0 of 5 checks used

Question 24
(1 points)

(#897130) {Tension}



Two masses,
�
1
m
​1
​​ = 3.68 kg and
�
2
m
​2
​​ = 6.30 kg, are connect by a string of negligible mass. The string passes over a frictionless pulley so that
�
1
m
​1
​​ and
�
2
m
​2
​​ hang down on opposite sides of the pulley. The whole system is released from rest. Calculate the tension in the string as the masses are moving.

Image size: SMLMax



Please enter a numerical answer below. Accepted formats are numbers or "e" based scientific notation e.g. 0.23, -2, 1e6, 5.23e-8

Enter answer here
N
No answer submitted
0 of 5 checks used
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