1.
The following is an excerpt from a letter sent by Henry Wallace to President Truman, July 23, 1946. From the
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. From the Harry S Truman Papers, Harry S Truman Library, Independence, Missouri. Henry Wallace, a former Vice President of the United States, was a critical observer of US policies during the start of the Cold War. He believed US actions were as much to blame as Soviet actions in the starting of the Cold War.
“How do American actions since V-J Day appear to other nations? I mean by actions the concrete things like $13 billion for the War and Navy Departments, the Bikini tests of the atomic bomb and continued production of bombs, the plan to arm Latin America with our weapons, production of B-29s and planned production of B-36s, and the effort to secure air bases spread over half the globe from which the other half of the globe can be bombed. I cannot but feel that these actions must make it look to the rest of the world as if we were only paying lip service to peace at the conference table.
These facts rather make it appear either (1) that we are preparing ourselves to win the war which we regard as inevitable or (2) that we are trying to build up a predominance of force to intimidate the rest of mankind. How would it look to us if Russia had the atomic bomb and we did not, if Russia had 10,000-mile bombers and air bases within a thousand miles of our coastlines, and we did not?
Our basic distrust of the Russians, … stems from differences in political and economic organization…I am convinced that we can meet that challenge as we have in the past by demonstrating that economic abundance can be achieved without sacrificing personal, political and religious liberties.
Our actions to expand our military security system-such steps as extending the Monroe Doctrine to include the arming of the Western Hemisphere nations, our present monopoly of the atomic bomb, our interest in outlying bases and our general support of the British Empire-appear to them as going far beyond the requirements of defense.”
Henry A. Wallace, Letter Sent to President Truman, July 23, 1946
Primary Source Document Questions:
1) What is the main idea contained within this document? (4 marks)
2) What is going on in the country/world when this document was written? (3 marks)
3) Is this document a reliable source? Why or why not? (Is there bias?) (3 marks)
4) What are 2 facts that you have learned in class or on your own that you can connect to this document? (2 marks)
5) How does this primary source contribute to our understanding of the time frame and/or history? (3 marks)
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2.A force of 40.0 N is needed to compress a spring 0.200 m. A 1.00 x 10-2 kg ball
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ring.
a) Calculate the work done to compress the spring. (2 marks)
b) What happens to the work done on the spring ? (1 mark)
c) If the spring is released, what happens to the energy of the spring? (1 mark)
d) Calculate the total mechanical energy of the ball at the instant it leaves the spring. (2 marks)
e) What will be the speed of the ball at the instant it leaves the spring? (2 marks)
f) If the ball is fired up into the air by the spring, how much gravitational potential energy will it gain? (1 mark)
g) What will be the maximum height of the ball? (2 marks
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6.2)Two books are accelerating to the right on a frictional surface and the coefficient of kinetic friction between the floor
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ction between the floor and book is µk. Using the information given in the figure:
(a) draw free body diagrams for both the books, and also for the combined system (of mass m1+m2),
(b) find acceleration of the books along horizontal direction, and
(c) find the magnitude and direction of the force exerted by the left book on the right book.
3.A car of mass 1500-kg enters a circular path at point P and leaves at point Q (see the figure) at constant speed of 5.0m/s, and the frictional force acting on its tires is 2500-N.
a) how long it takes to reach point Q from point P, and
b) what should be the minimum value of the coefficient of static friction between the tires and the road?
4)In an elevator which is accelerating downward at 2.5ms−2 , a 25-kg block hangs from a spring attached to the ceiling of the elevator. If spring gets stretched by 0.15m, find its spring constant.
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7.1) Which of the following statements about scientific methods / theories is correct?
(1/0/0)
a) A scientific theory must be able to
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a) A scientific theory must be able to be proven.
b) A scientific theory has been derived from known facts and always applies.
c) A scientific method should give different results depending on who performs the method.
d) Knowledge of our surroundings usually emerges through an interplay between theory and experiment.
2) The sides of a straight block are measured to 3,202 cm; 0.0012 cm and 11.2 cm, respectively. Calculate the volume of the straightening block and enter it with the correct number of value digits.
(2/0/0)
Number of words: 0
3) A 9.2 dm long and evenly thick rod rests on a support. 0.55 dm from one end, a dynamometer is hung so that the rod will hang horizontally. Then the dynamometer shows 4.4 N. How much does the bar weigh?
(1/1/0)
Number of words: 0
4) A bar AB that is homogeneous and evenly thick has a length of 2.70 m and is rotatable about an axis at A. The bar weighs 25 kg and is kept in equilibrium by a force F which has its point of attack in B. is 45 degrees. How big is the force F?
(1/1/0)
Saved!
25 * 9.82 = 245.5 N
Number of words: 6
5) A trolley rolls at a constant speed to the right. On the cart is an upward cannon that suddenly shoots a bullet. The carriage continues to the right with the same speed as before. Where does the bullet end up when it falls? For a detailed reasoning.
(1/1/1)
Number of words: 0
6) A river is 200 m wide. The water in the river flows at a speed of 2.5 m / s. A motorboat steers across the river at its maximum speed, which in stagnant water is 5.0 m / s. The boat is constantly heading perpendicular to the banks of the river. Where does the motorboat land on the other shore?
(2/0/0)
Number of words: 0
7) A ball with a mass of 2.0 hg moves at a constant speed in a circular path. The radius of the track is 1.5 m and it takes the ball 3.0 seconds to move one turn. How big is the centripetal force?
(1/1/0)
Number of words: 0
8) A bullet moves at a constant speed. Can we then safely say that the resultant of the forces acting on the bullet is zero? Motivate and discuss your answer.
(0/1/1)
Number of words: 0
9) A conductor is located between the poles of a permanent magnet. The current in the conductor goes in the direction of the plane of the paper (away from the reader). How is the force acting on the leader directed?
(1/0/0)
a) To the right of the figure
b) To the left in the figure
c) Downwards in the figure
d) Upwards in the figure
10) Protons enter horizontally from the left between two large metal plates at a speed v = 0.80 Mm / s. The plates are connected to a voltage source with the pole voltage U. Between the plates there is a homogeneous magnetic field with a flux density of 38 mT directed perpendicular to the plane of the paper. The distance between the plates is 1.5 cm. They want the protons to continue with unchanged direction and speed between the plates. Which of the plates should be connected to the positive pole of the voltage source and how large should the voltage U be?
(0/2/0)
Number of words: 0
11) The magnetic flux Φ through a 700-speed coil decreases linearly with time according to the diagram below. Calculate the voltage across the coil at time t = 1.0 ms.
12) The current in a coil with an inductance of 35 mH has a growth rate of 6.2 A / s at a given moment. What is the instantaneous value of the ems induced in the coil?
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8.A sphere of mass M = 20kg and radius R = 10cm has its mass distributed in a way where
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mediately guess it’s moment of inertia. To investigate whether it behaves more like a solid sphere or hollow sphere, you roll it down a rough ramp inclined at an angle of 30° with respect to the horizontal. The sphere rolls without slipping and you measure the velocity of the center of mass to be 3 m/s as it leaves the bottom of the ramp. The ramp’s length is 2 m and you release the sphere from the top of the ramp, a height of 1 m.
a) What is the moment of inertia of the sphere?
b) What is the angular speed of the sphere as it reaches the bottom of the ramp?
c) What is the frictional force on the sphere?
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10.Let's Play Ice Hockey!
9601686.png
An ice hockey player uses hockey stick to apply force on a motionless puck as shown on
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motionless puck as shown on the picture above. The net force that the stick applies on the puck is 150N and the contact lasts for 7.5 ms. The mass of the puck is 166 g.
A) (1 point) Calculate the acceleration of the puck under the influence of the net force.
B) (2 points) Calculate the puck's change in momentum due to the impulse applied by the hockey stick.
C) (1 point) What is the velocity of the puck once it leaves the stick?
Puck travels over rough ice and comes to a stop after 25 m. The force diagram below shows all forces acting on the puck during that travel.
Screen Shot 2020-11-02 at 2.04.05 PM.png
D) (1 point) Calculate the work done on the puck by gravitational force.
E) (1 point) Calculate the work done on the puck by normal force.
F) (2 points) Calculate work done by friction force on the puck.
CNX_UPhysics_09_03_HockeyPuck.jpg
Now stationary, the puck (red) collides with a blue puck of the mass .332 kg moving to the left with velocity of 2.5 m/s. If collision is perfectly elastic calculate:
H) (2 points) Total momentum of blue+red puck system before collision?
I) (1 point) What is the total momentum of blue+red puck system after collision? How do you know?
J) (2 points) What is the velocity of the blue puck after collision?
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11.27. The Air force receives 30% of its parachutes from company C1 and the rest from company C2. The probability
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robability that a parachute will fail to open is 0.0025 and 0.002, depending on whether it is from company C1 or C2, respectively.
a) What is the probability that a randomly chosen parachute will fail to open (rounded off to four decimals)?
b) If a randomly chosen parachute fails, what is the probability it came from company C1 (rounded off to four decimals)?
c) If a randomly chosen parachute fails, what is the probability it came from company C2 (rounded off to four decimals)?
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12.Hi, is it perhaps possible that I can get some assistance with the following question below? specifically b) and c)
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cally b) and c) please?
The Air force receives 30% of its parachutes from company C1 and the rest from company C2. The probability that a parachute will fail to open is 0.0025 and 0.002, depending on whether it is from company C1 or C2, respectively.
a) What is the probability that a randomly chosen parachute will fail to open (rounded off to four decimals)?
Ans=0.0022
b) If a randomly chosen parachute fails, what is the probability it came from company C1 (rounded off to four decimals)?
c) If a randomly chosen parachute fails, what is the probability it came from company C2 (rounded off to four decimals)?
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15.An elevator WEIGHS 1.0 x 10⁴ N. {Part A} Draw a free body diagram for each part of this questions
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to show which force is larger [5 marks] {Part B} Determine the MASS of the elevator [2 marks] {Part C} The elevator begins to accelerate UPWARDS from rest at 5.0 m/s². What is the force tension in the cable? [3 marks] {Part D} The same elevator is moving UPWARDS and starts to DECELERATE at 3.0 m/s². What is the force tension in the cable? [3 marks] {Part E} The elevator moves DOWN at CONSTANT velocity at 10 m/s. What is the force tension in the cable? [2 marks] {Part F} The elevator cable snaps (and everyone screams!). What are the forces working on the elevator now? Draw a diagram [2 marks]
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22.Use g = 9.8 m/s2.
The diagram below is a top-down view of two children pulling a 11.8-kg sled along the
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ng the snow. The first child exerts a force of F1 = 11 N at an angle θ1 = 45° counterclockwise from the positive x direction. The second child exerts a force of F2 = 6 N at an angle θ2 = 30° clockwise from the positive x direction.
Find the magnitude (in N) and direction of the friction force acting on the sled if it moves with constant velocity.
magnitude
direction (counterclockwise from the +x-axis)
What is the coefficient of kinetic friction between the sled and the ground?
What is the magnitude of the acceleration (in m/s2) of the sled if F1 is doubled and F2 is halved in magnitude?
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24.A uniform beam of length L
and mass m shown in Figure
P12.16 is inclined at an angle
u to the horizontal. Its
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izontal. Its upper
end is connected to a wall by
a rope, and its lower end rests
on a rough, horizontal sur-
face. The coefficient of static
friction between the beam
and surface is ms. Assume
the angle u is such that the static friction force is at its
maximum value. (a) Draw a force diagram for the beam.
(b) Using the condition of rotational equilibrium,
find an expression for the tension T in the rope in
terms of m, g, and u. (c) Using the condition of trans-
lational equilibrium, find a second expression for T in
terms of ms, m, and g. (d) Using the results from parts
(a) through (c), obtain an expression for ms
L
u
Figure P12.16
Q/C
S
vertical component of this force. Now solve the same
problem from the force diagram from part (a) by com-
puting torques around the junction between the cable
and the beam at the right-hand end of the beam. Find
(e) the vertical component of the force exerted by the
pole on the beam, (f) the tension in the cable, and
(g) the horizontal component of the force exerted
by the pole on the beam. (h) Compare the solution
to parts (b) through (d) with the solution to parts
(e) through (g). Is either solution more accurate?
19. Sir Lost-a-Lot dons his armor and sets out from the
castle on his trusty steed (Fig. P12.19). Usually, the
drawbridge is lowered to a horizontal position so that
the end of the bridge rests on the stone ledge. Unfor-
tunately, Lost-a-Lot’s
squire didn’t lower the draw-
involv-
ing only the angle u. (e) What happens if the ladder
is lifted upward and its base is placed back on the
ground slightly to the left of its position in Figure
P12.16? Explain.
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