Chapter Pretests


Chapter 4 Quiz
 
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Chapter 4 Quiz


Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
A 200-N crate rests on an ramp; the maximum angle just before it slips is 25° with the horizontal. What is the coefficient of static friction between crate and ramp surfaces?
a.
0.47
b.
0.38
c.
0.52
d.
0.21
e.
0.11
 

 2. 
Three identical 6.0-kg cubes are placed on a horizontal frictionless surface in contact with one another. The cubes are lined up from left to right and a 36-N force is applied to the left side of the left cube causing all three cubes to accelerate to the right. If the cubes are each subject to a frictional force of 6.0 N, what is the magnitude of the force exerted on the middle cube by the left cube in this case?
a.
24 N
b.
12 N
c.
36 N
d.
48 N
e.
none of the above
 

 3. 
The accelerating force of the wind on a small 200-kg sailboat is 707 N northeast. If the drag of the keel is 500 N acting west, what is the acceleration of the boat?
a.
3.0 m/s2 northeast
b.
1.5 m/s2 due west
c.
1.5 m/s2 due east
d.
2.0 m/s2 north by northwest
e.
2.5 m/s2 due north
 

 4. 
A 10-kg mass and a 2.0-kg mass are connected by a light string over a massless, frictionless pulley. If g = 9.8 m/s2, what is the acceleration of the system when released?
a.
2.5 m/s2
b.
7.8 m/s2
c.
6.5 m/s2
d.
9.8 m/s2
e.
9.9 m/s2
 

 5. 
A thrown stone hits a window, but doesn't break it. Instead it reverses direction and ends up on the ground below the window. In this case, we know:
a.
the force of the stone on the glass = the force of the glass on the stone.
b.
No conclusion can be made with the information given.
c.
the force of the stone on the glass < the force of the glass on the stone.
d.
the stone didn't slow down as it broke the glass.
e.
the force of the stone on the glass > the force of the glass on the stone.
 

 6. 
The acceleration due to gravity on the Moon's surface is one-sixth that on Earth. An astronaut's life support backpack weighs 300 lbs on Earth. What does it weigh on the Moon?
a.
40 lb
b.
1 800 lb
c.
50 lb
d.
300 lb
e.
135 lb
 

 7. 
Two blocks, joined by a string, have masses of 6.0 and 9.0 kg. They rest on a frictionless horizontal surface. A 2nd string, attached only to the 9-kg block, has horizontal force = 30 N applied to it. Both blocks accelerate. Find the tension in the string between the blocks.
a.
16 N
b.
15 N
c.
28 N
d.
18 N
e.
12 N
 

 8. 
A sled weighs 100 N. It is held in place on a frictionless 20° slope by a rope attached to a stake at the top; the rope is parallel to the slope. What is the normal force of the slope acting on the sled?
a.
94 N
b.
37 N
c.
28 N
d.
34 N
e.
47 N
 

 9. 
It is late and Carlos is sliding down a rope from his third floor window to meet his friend Juan. As he slides down the rope faster and faster, he becomes frightened and grabs harder on the rope, increasing the tension in the rope. As soon as the upward tension in the rope becomes equal to his weight:
a.
Carlos will slow down.
b.
Carlos will accelerate.
c.
Carlos will continue down at a constant velocity.
d.
Carlos will stop.
e.
the rope must break.
 

 10. 
A 2 000-kg sailboat experiences an eastward force of 3 000 N by the ocean tide and a wind force against its sails with magnitude of 6 000 N directed toward the northwest (45° N of W). What is the magnitude of the resultant acceleration?
a.
1.2 m/s2
b.
1.5 m/s2
c.
3.0 m/s2
d.
2.1 m/s2
e.
2.2 m/s2
 

 11. 
A 20-kg traffic light hangs midway on a cable between two poles 40 meters apart. If the sag in the cable is 0.40 meters, what is the tension in each side of the cable?
a.
980 N
b.
3 200 N
c.
12 000 N
d.
9 800 N
e.
4 900 N
 

 12. 
The coefficient of static friction between the tires of a car and the street is µs = 0.77. Of the following, what is the steepest inclination angle of a street on which a car can be parked (with wheels locked) without slipping?
a.
54°
b.
45°
c.
37°
d.
22.5°
e.
30°
 

 13. 
Find the tension in an elevator cable if the 1 000-kg elevator is descending with an acceleration of 1.8 m/s2, downward.
a.
12 800 N
b.
9 800 N
c.
11 600 N
d.
5 700 N
e.
8 000 N
 

 14. 
Jamal pulls a 150-N sled up a 28.0° slope at constant speed by a force of 100 N. Near the top of the hill he releases the sled. With what acceleration does the sled go down the hill?
a.
1.20 m/s2
b.
3.26 m/s2
c.
1.67 m/s2
d.
2.22 m/s2
e.
2.67 m/s2
 

 15. 
Two blocks of masses 20 kg and 8 kg are connected together by a light string and rest on a frictionless level surface. Attached to the 8-kg mass is another light string, which a person uses to pull both blocks horizontally. If the two-block system accelerates at 0.5 m/s2 what is the tension in the connecting string between the blocks?
a.
9.0 N
b.
6 N
c.
14 N
d.
4.0 N
e.
10 N
 

 16. 
An astronaut applies a force of 500 N to an asteroid, and it accelerates at 7.00 m/s2. What is the asteroid's mass?
a.
441 kg
b.
135 kg
c.
71 kg
d.
3 500 kg
e.
3.600 kg
 

 17. 
The maximum possible value for the coefficient of static friction is:
a.
1.00.
b.
a value up to but not quite 1.00.
c.
greater than 1.00.
d.
0.50.
e.
0.94.
 

 18. 
A horizontal force of 750 N is needed to overcome the force of static friction between a level floor and a 250-kg crate. If g = 9.8 m/s2, what is the coefficient of static friction?
a.
3.0
b.
0.15
c.
2.5
d.
0.28
e.
0.31
 

 19. 
A 100-kg box is placed on a ramp. As one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 15°. What is the coefficient of static friction between box and ramp?
a.
0.98
b.
0.27
c.
0.15
d.
0.95
e.
0.77
 

 20. 
Two ropes are attached to a 40-kg object. The first rope applies a force of 25 N and the second, 40 N. If the two ropes are perpendicular to each other, what is the resultant acceleration of the object?
a.
25 m/s2
b.
3.0 m/s2
c.
1.2 m/s2
d.
47 m/s2
e.
5.0 m/ s2
 



 
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