| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.97 |
| Score | 0% | 59% |
Which of the following is not a type of simple machine?
screw |
|
pulley |
|
gear |
|
lever |
The six types of simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw.
| 12 | |
| 4 | |
| 6 | |
| 2 |
The gear ratio (Vr) of a gear train is the product of the gear ratios between the pairs of meshed gears. Let N represent the number of teeth for each gear:
Vr = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) \( \frac{N_3}{N_4} \) ... \( \frac{N_n}{N_{n+1}} \)
In this problem, we have only two gears so the equation becomes:Vr = \( \frac{N_1}{N_2} \) = \( \frac{32}{8} \) = 4
Which of the following represents the force a surface exerts when an object presses against it?
mass |
|
normal force |
|
counter force |
|
friction |
Normal force (FN) represents the force a surface exerts when an object presses against it.
Two gears are connected and the larger gear drives the smaller gear. The speed of rotation will __________ and the torque will __________.
decrease, decrease |
|
decrease, increase |
|
increase, increase |
|
increase, decrease |
Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.
| 10 | |
| 2.0 | |
| 5 | |
| 0.5 |
The mechanical advantage of a wheel and axle is the input radius divided by the output radius:
MA = \( \frac{r_i}{r_o} \)
In this case, the input radius (where the effort force is being applied) is 10 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{10}{5} \) = 2.0