|
| 1 | When considering only concurrent forces, we do not need to calculate torques. |
 | A) | True |
| B) | False |
|
| 2 | If an object is suspended from the ceiling by a rope attached to its center of gravity, the system will attain equilibrium. |
| A) | True |
| B) | False |
|
| 3 | The moment arm is the distance from the point of application of a force to the axis of rotation. |
| A) | True |
| B) | False |
|
| 4 | When a force tends to cause clockwise rotation, it produces a positive torque by convention. |
| A) | True |
| B) | False |
|
| 5 | In applying the second condition for equilibrium, the axis of rotation may be chosen for convenience. |
| A) | True |
| B) | False |
|
| 6 | The center of gravity of a body is always at the geometrical center of the body. |
| A) | True |
| B) | False |
|
| 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. |
| A) | True |
| B) | False |
|
| 8 | In computing the resultant torque, the axis of rotation may be chosen for convenience. |
| A) | True |
| B) | False |
|
| 9 | The unit of torque in the metric system is the newton-meter. |
| A) | True |
| B) | False |
|
| 10 | The net torque will be the same if a force is doubled but moved to a point halfway to the axis of rotation. |
| A) | True |
| B) | False |
|
| 11 | To apply the second condition for equilibrium, the axis of rotation |
| 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 |
|
| 12 | To compute torque, one must know |
| A) | the force magnitude |
| B) | the moment arm |
| C) | both of these |
| D) | neither of these |
|
| 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? |
| A) | -20 lb · ft |
| B) | +20 lb · ft |
| C) | -10 lb · ft |
| D) | 10 lb · ft |
|
| 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 |
| A) | -120 lb · ft |
| B) | +20 lb · ft |
| C) | +120 lb · ft |
| D) | 240 lb · ft |
|
| 15 | Which of the following is not a unit of torque? |
| A) | Pound-foot |
| B) | Kilogram-newton |
| C) | Newton-meter |
| D) | Pound-inch |
|
| 16 | If the resultant of a set of concurrent forces is zero, the sum of the torques |
| A) | is also zero |
| B) | may or may not be zero |
| C) | is not zero |
| D) | depends on the axis of rotation |
|
| 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 |
| A) | 4 lb |
| B) | 2 lb |
| C) | 3.6 lb |
| D) | 5 lb |
|
| 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? |
| A) | 90 lb |
| B) | 75 lb |
| C) | 200 lb |
| D) | 180 lb |
|
| 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? |
| A) | 13.3 N |
| B) | 26.7 N |
| C) | 40 N |
| D) | 80 N |
|
| 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
 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0077158733/294231/fig53.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (19.0K)</a>]]> |
| A) | 310 N |
| B) | 352 N |
| C) | 424 N |
| D) | 512 N |
|
| 21 | The distance from the line of action of a force to the point of rotation is known as the . |
|
| 22 | The of a body is that point at which all the weight of the body may be considered to be concentrated. |
|
| 23 | The second condition for equilibrium states that the sum of all the acting on an object must be . |
|
| 24 | By convention, torques that tend to cause clockwise motion are considered , and those that tend to cause counterclockwise motion are considered . |
|
| 25 | If the line of action of a force passes through the axis of rotation, the moment arm is . |
|
| 26 | In problems involving nonconcurrent forces, both the resultant and the resultant must be zero. |
|
| 27 | The unit for moment of force in the SI system is the . |
|
| 28 | The center of gravity of a regular solid of uniform density, such as a sphere or cube, is located at . |
|
| 29 | An alternate way of computing the torque due to a single force is to resolve the force into parallel and perpendicular components and . |
|
| 30 | Three tools that utilize the principle of torque are , , and . |