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1.
Description
This assignment is worth 20 points. Each part is worth 1 point.
Assume the numbers given in each problem are accurate to three significant figures. WebAssign expects your
answers to be accurate within 1%. If you don't round off until the end, and then round off to three significant figures, you
should be fine.
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incorrectly please check with Professor Duffy.
0/2 pointsDuffy_EP_Ch03_P12 [1016680]
Four free-body diagrams are shown below, for objects that have masses of m, 2m, 3m, and 4m, respectively. In each
free-body diagram, the upward normal force exactly balances the downward force of gravity.
(a) Rank these situations, from largest to smallest, based on the magnitude of the net force applied to the object. Use only
"greater than" signs and "equals" signs in your ranking, such as 3>2=4>1
3>4>1=2 -or- 3>4>2=1
(b) Rank these situations, from largest to smallest, based on the magnitude of the object's acceleration. Use only "greater
than" signs and "equals" signs in your ranking, such as 3>2=4>1
1=3>2>4 -or- 3=1>2>4
2.
0/1 pointsDuffy_EP_Ch03_P36 [1184172]
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Consider the motion diagram shown in the figure above. The vertical lines in the diagram are 100. cm apart, the object has a
mass of 5.00 kg, and the images of the object are shown at intervals of 3.00 seconds. Determine the magnitude of the net
force being applied to the object if the object is moving from right to left with a constant acceleration.
1.11 N
3.
0/3 pointsDuffy_EP_Ch03_P43 [1184268]
A solar sail is a space probe that is propelled by sunlight reflecting off a shiny sail with a large area. Let’s say the probe and
sail have a combined mass of 2000 kg and that the net force exerted on the system is 6.00 N directed away from the Sun.
(a) What is the acceleration of this solar sail?
0.003 m/s2
The net force will actually decrease in magnitude as the probe gets farther from the Sun, but let’s not worry about that. If the
system is released from rest, how fast will it be traveling after...
(b) 1 day?
259 m/s
(c) 1 week?
4.
1810 m/s
0/1 pointsWiley Simulation 17.3 [198569]
Newton's Second Law
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Consider these four cases:
Case 1: Mass = 4.0 kg; Force 1 = 8 N; Force 2 = 2 N; Force 3 = -2 N.
Case 2: Mass = 3.5 kg; Force 1 = 8 N; Force 2 = 0; Force 3 =0.
Case 3: Mass = 2.0 kg; Force 1 = 7 N; Force 2 = 3 N; Force 3 = -2 N.
Case 4: Mass = 2.0 kg; Force 1 = 4 N; Force 2 = 0; Force 3 = 0.
5.
(a) Rank these cases by the distance traveled by the block in 3 seconds in each case, from largest to smallest. Use
only > and/or = signs, e.g., 4>2=3>1. See if you can work out the correct ranking yourself, and then use the
simulation to verify your answer.
3>2>1=4 -or- 3>2>4=1
0/3 pointsWiley Simulation 17.1. [190172]
Newton's Second Law
In the simulation above the motion continues for 3 seconds. If the object travels a distance of 42.0 m in that time determine:
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(a) the acceleration of the object during the 3-second period.
9.33 m/s2
(b) the maximum speed of the object during the 3-second period.
28 m/s
(c) If the mass of the object is 1.50 kg, force 1 is 7 N and force 2 is 5 N, what is force 3 set to?
2 N
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6.
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0/3 pointsDuffy_EP_Ch03_P18 [1184317]
Two boxes are side-by-side on a frictionless horizontal surface as shown in the figure above. In case (a), a horizontal force F
directed right is applied to the box of mass M, which we will call box 1. In case (b), the horizontal force F is instead applied to
the box of mass m, which we will call box 2. We know that M > m.
(a) Considering the situation shown in case (a) only, choose all the correct statements regarding the free-body diagrams
shown above.
The correct free-body diagram of the two-box system is FBD 1.
The correct free-body diagram of box 1 is FBD 2.
The correct free-body diagram of box 1 is FBD 3.
The correct free-body diagram of box 2 is FBD 4.
The correct free-body diagram of box 2 is FBD 5.
The correct free-body diagram of box 2 is FBD 6.
(b) Select the two correct statements from the list below.
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The magnitude of the acceleration of the two-box system is larger in case (a)
than it is in case (b).
The magnitude of the acceleration of the two-box system is smaller in case (a)
than it is in case (b).
The magnitude of the acceleration of the two-box system is equal in both
cases.
The magnitude of the acceleration of the box of mass m is larger in case (a) than
it is in case (b).
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The magnitude of the acceleration of the box of mass m is smaller in case (a)
than it is in case (b).
The magnitude of the acceleration of the box of mass m is equal in both
cases.
(c) Once again, select the two correct statements from the list below.
7.
The magnitude of the force that the larger box exerts on the smaller box is larger
in case (a) than it is in case (b).
The magnitude of the force that the larger box exerts on the smaller box is
smaller in case (a) than it is in case (b).
The magnitude of the force that the larger box exerts on the smaller box is equal
in both cases.
The magnitude of the force that the smaller box exerts on the larger box is larger
in case (a) than it is in case (b).
The magnitude of the force that the smaller box exerts on the larger box is
smaller in case (a) than it is in case (b).
The magnitude of the force that the smaller box exerts on the larger box is equal
in both cases.
0/4 pointsDuffy_EP_Ch03_P50 [1184295]
As shown above, three blocks are tied in a vertical line by three strings, and the top string is tied to the ceiling of an elevator.
Use g = 10 m/s2. What is the magnitude of the tension in string 3 if the elevator is...
(a) at rest?
50 N
(b) moving at a constant velocity of 3.00 m/s up?
50 N
(c) accelerating up at 2.00 m/s2?
60 N
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(d) accelerating down at 4.00 m/s2?
30 N
8.
0/3 pointsDuffy_EP_Ch03_P51_alt [1016692]
Try doing this problem without a calculator. Three blocks are placed side-by-side on a frictionless horizontal surface and
subjected to a horizontal force F, that causes the blocks to accelerate from rest to the right. Consider case 2 only.
In case 2, if the horizontal force F is 80.0 N what is:
(a) The magnitude of the acceleration of the system?
8 m/s2
(b) The magnitude of the net force acting on the 2.0 kg block?
16 N
(c) The magnitude of the force exerted by the 5.0 kg block on the 2.0 kg block?
64 N
Just for fun, think about whether any of your answers would change if we asked the same questions about case 1.
Assignment Details
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