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1 | |
The efficiency of a machine is defined as the ratio of the work input to the work output. |
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| | A) | True |
| | B) | False |
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2 | |
The actual mechanical advantage of a machine can never be less than unity. |
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| | A) | True |
| | B) | False |
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3 | |
The wheel and axle is an application of the principle of the lever. |
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| | A) | True |
| | B) | False |
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4 | |
A single fixed pulley offers no mechanical advantage; it changes only the direction of an input force. |
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| | A) | True |
| | B) | False |
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5 | |
In a pulley system with a speed ratio greater than 1, the output torque is less than the input torque. |
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| | A) | True |
| | B) | False |
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6 | |
In a machine using two gears in which the number of teeth on the input gear is greater than the number of teeth on the output gear, there will be a reduction in the output torque. |
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| | A) | True |
| | B) | False |
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7 | |
The speed ratio ωi/ωo represents the ideal mechanical advantage and not the actual mechanical advantage. |
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| | A) | True |
| | B) | False |
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8 | |
In a belt drive, maximum efficiency is obtained for minimum belt tension. |
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| | A) | True |
| | B) | False |
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9 | |
For an inclined plane, the actual mechanical advantage is the ratio of the slope distance to the height of the plane. |
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| | A) | True |
| | B) | False |
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10 | |
For a screw jack, a larger pitch results in a smaller mechanical
advantage. |
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| | A) | True |
| | B) | False |
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11 | |
Which of the following ratios does not represent the mechanical advantage of a machine? |
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| | A) | Do/Di |
| | B) | ωo/ωi |
| | C) | No/Ni |
| | D) | Fo/Fi |
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12 | |
Which of the following is not an indication of the efficiency of a machine? |
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| | A) | MA/MI |
| | B) | Po/Pi |
| | C) | Foro/(Firi) |
| | D) | Loωo/(Liωi) |
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13 | |
The actual mechanical advantage may be increased for a given machine by |
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| | A) | increasing Fi |
| | B) | increasing Fo |
| | C) | lubrication |
| | D) | none of these |
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14 | |
Which of the following machines is not an application of the lever principle? |
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| | A) | Screw jack |
| | B) | Wheelbarrow |
| | C) | Wheel and axle |
| | D) | Pliers |
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15 | |
An 80-hp motor has an efficiency of 60 percent. The output power is approximately |
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| | A) | 133 hp |
| | B) | 75 hp |
| | C) | 60 hp |
| | D) | 48 hp |
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16 | |
An iron pipe 10 ft long is used to lift a 400-lb weight. If the fulcrum is placed 2 ft from the weight, the force that must be exerted at the end of the pipe is approximately |
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| | A) | 200 lb |
| | B) | 100 lb |
| | C) | 40 lb |
| | D) | 80 lb |
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17 | |
The ideal mechanical advantage of a belt drive is 4.0. If the angular speed of the input pulley is 8 rad/s, the angular speed of the output pulley is |
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| | A) | 2 rad/s |
| | B) | 32 rad/s |
| | C) | 0.5 rad/s |
| | D) | 4 rad/s |
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18 | |
A 100-lb box is pushed up a 200-ft ramp to a height of 20 ft. The ideal mechanical advantage is approximately |
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| | A) | 4 |
| | B) | 10 |
| | C) | 5 |
| | D) | 0.1 |
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19 | |
Consider a belt drive in which the diameter of the driving pulley is 8 cm and the diameter of the driven pulley is 24 cm. If the efficiency is 50 percent, what is the actual mechanical advantage? |
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| | A) | 15 |
| | B) | 6 |
| | C) | 1.5 |
| | D) | 3 |
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20 | |
In the operation of a screw jack of pitch 0.1 in., the input force of 4 lb turns through a circle of radius 2 ft, lifting an 80-lb weight. The efficiency is approximately |
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| | A) | 48 percent |
| | B) | 14.4 percent |
| | C) | 20 percent |
| | D) | 1.3 percent |
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21 | |
The efficiency of a machine is defined as the ratio of the to the . |
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22 | |
In general, for a simple machine the is defined as the ratio of the output force to the input force. The is the ratio of the distance the force moves to the distance the force moves. |
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23 | |
Three applications of the lever principle are demonstrated by the following tools: , , and . |
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24 | |
If the speed ratio is greater than 1, the machine produces an output torque than the input torque. |
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25 | |
Three common types of gears are , , and . |
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26 | |
The ideal mechanical advantage of a wedge is equal to its plus the . |
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27 | |
For a simple machine, the work input is equal to the plus the . |
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28 | |
The ideal mechanical advantage of a set of gears is equal to the ratio of the on the output gear to the on the input gear. |
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29 | |
For a screw jack, the reciprocal of the number of threads per inch is the of the screw. |
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30 | |
In a single movable pulley, the input force moves through the distance that the output force moves, resulting in a mechanical advantage of . |
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