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1 | |
When considering only concurrent forces, we do not need to calculate torques. |
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| | A) | True |
| | B) | False |
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2 | |
If an object is suspended from the ceiling by a rope attached to its center of gravity, the system will attain equilibrium. |
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| | A) | True |
| | B) | False |
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3 | |
The moment arm is the distance from the point of application of a force to the axis of rotation. |
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| | A) | True |
| | B) | False |
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4 | |
When a force tends to cause clockwise rotation, it produces a positive torque by convention. |
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| | A) | True |
| | B) | False |
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5 | |
In applying the second condition for equilibrium, the axis of rotation may be chosen for convenience. |
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| | A) | True |
| | B) | False |
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6 | |
The center of gravity of a body is always at the geometrical center of the body. |
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| | A) | True |
| | B) | False |
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7 | |
In applying the second condition for equilibrium, it is acceptable to equate the clockwise torques about any axis to the counterclockwise torques about the same axis. |
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| | A) | True |
| | B) | False |
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8 | |
In computing the resultant torque, the axis of rotation may be chosen for convenience. |
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| | A) | True |
| | B) | False |
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9 | |
The unit of torque in the metric system is the newton-meter. |
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| | A) | True |
| | B) | False |
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10 | |
The net torque will be the same if a force is doubled but moved to a point halfway to the axis of rotation. |
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| | A) | True |
| | B) | False |
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11 | |
To apply the second condition for equilibrium, the axis of rotation |
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| | A) | must be at the center of the body |
| | B) | must be at one end |
| | C) | may be chosen anywhere |
| | D) | must be at the center of gravity |
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12 | |
To compute torque, one must know |
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| | A) | the force magnitude |
| | B) | the moment arm |
| | C) | both of these |
| | D) | neither of these |
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13 | |
A rope is wrapped in a clockwise direction around a 12-in.-diameter axle. If a force of 20 lb is exerted on the rope, what is the resultant torque? |
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| | A) | -20 lb · ft |
| | B) | +20 lb · ft |
| | C) | -10 lb · ft |
| | D) | 10 lb · ft |
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14 | |
A 60-lb boy sits on the left end of a 12-ft seesaw, and a 40-lb boy sits on the right end. The resultant torque about the center is approximately |
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| | A) | -120 lb · ft |
| | B) | +20 lb · ft |
| | C) | +120 lb · ft |
| | D) | 240 lb · ft |
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15 | |
Which of the following is not a unit of torque? |
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| | A) | Pound-foot |
| | B) | Kilogram-newton |
| | C) | Newton-meter |
| | D) | Pound-inch |
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16 | |
If the resultant of a set of concurrent forces is zero, the sum of the torques |
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| | A) | is also zero |
| | B) | may or may not be zero |
| | C) | is not zero |
| | D) | depends on the axis of rotation |
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17 | |
A 20-lb uniform board is 16 ft long and is supported at a point 6 ft from the right end. The upward force that must be exerted at the left end to balance the system is approximately |
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| | A) | 4 lb |
| | B) | 2 lb |
| | C) | 3.6 lb |
| | D) | 5 lb |
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18 | |
A rope is wrapped around a 16-in.-diameter drum in a counterclockwise direction. What force must be exerted on the rope to give a torque of 120 lb · ft? |
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| | A) | 90 lb |
| | B) | 75 lb |
| | C) | 200 lb |
| | D) | 180 lb |
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19 | |
A girl and a boy carry a sack weighing 40 N on a pole between them. If the pole is 6 m long and the load is 2 m from the girl, what force does the boy exert? |
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| | A) | 13.3 N |
| | B) | 26.7 N |
| | C) | 40 N |
| | D) | 80 N |
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20 | |
The boom in Fig. 5-3 is 2 m long and weighs 100 N. If the 800-N load is suspended 50 cm from the end, the cable tension is approximately
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| | A) | 310 N |
| | B) | 352 N |
| | C) | 424 N |
| | D) | 512 N |
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21 | |
The distance from the line of action of a force to the point of rotation is known as the . |
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22 | |
The of a body is that point at which all the weight of the body may be considered to be concentrated. |
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23 | |
The second condition for equilibrium states that the sum of all the acting on an object must be . |
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24 | |
By convention, torques that tend to cause clockwise motion are considered , and those that tend to cause counterclockwise motion are considered . |
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25 | |
If the line of action of a force passes through the axis of rotation, the moment arm is . |
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26 | |
In problems involving nonconcurrent forces, both the resultant and the resultant must be zero. |
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27 | |
The unit for moment of force in the SI system is the . |
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28 | |
The center of gravity of a regular solid of uniform density, such as a sphere or cube, is located at . |
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29 | |
An alternate way of computing the torque due to a single force is to resolve the force into parallel and perpendicular components and . |
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30 | |
Three tools that utilize the principle of torque are , , and . |
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