| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.02 |
| Score | 0% | 60% |
| 3 | |
| 4 | |
| 0.75 | |
| -1 |
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 3 and the output radius (where the resistance is being applied) is 4 for a mechanical advantage of \( \frac{3}{4} \) = 0.75
| 4.4 | |
| 7 | |
| 4 | |
| 5.5 |
The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:
MA = \( \frac{d_e}{d_r} \) = \( \frac{28 ft.}{7 ft.} \) = 4
Which of the following is not a modulus of elasticity?
stretch modulus |
|
shear modulus |
|
bulk modulus |
|
stress modulus |
The modulus of elasticity measures how much a material or structure will deflect under stress. Stretch modulus is longitudinal stretch (like stretching raw bread dough), shear modulus is longitudinal deflection (like the horizontal displacement of a stack of magzines when a heavy object is placed upon them), and bulk modulus is compression of volume (like the compression of a loaf of bread under a heavy can at the bottom of a grocery bag).
The principle of moments defines equilibrium in terms of:
energy |
|
power |
|
torque |
|
speed |
According to the principle of moments, you can maintain equilibrium if the moments (forces) tending to clockwise rotation are equal to the moments tending to counterclockwise rotation. Another name for these moments of force is torque.
| 1170 lbs. | |
| 390 lbs. | |
| 3510 lbs. | |
| 1164 lbs. |
The mechanical advantage (MA) of a block and tackle pulley is equal to the number of times the effort force changes direction. An easy way to count how many times the effort force changes direction is to count the number of ropes that support the resistance which, in this problem, is 6. With a MA of 6, a 195 lbs. effort force could lift 195 lbs. x 6 = 1170 lbs. resistance.