| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.15 |
| Score | 0% | 63% |
| 26.22 lbs. | |
| 10.67 lbs. | |
| 24 lbs. | |
| 8.01 lbs. |
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 8 and the output radius (where the resistance is being applied) is 3 for a mechanical advantage of \( \frac{8}{3} \) = 2.67
MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{70 lbs.}{2.67} \) = 26.22 lbs.
Boyle's law defines the relationship between pressure and volume as:
\(\frac{P_1}{P_2} = \frac{V_1}{V_2}\) |
|
\({P_1}{P_2} = {V_1}{V_2}\) |
|
\(\frac{P_1}{P_2} = \frac{V_2}{V_1}\) |
|
\(\frac{P_1}{P_2} = {V_1}{V_2}\) |
Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional". Expressed as a formula, that's \(\frac{P_1}{P_2} = \frac{V_2}{V_1}\)
Potential energy is energy that has the potential to be converted into what?
kinetic energy |
|
heat |
|
power |
|
work |
Potential energy is the energy of an object by virtue of its position relative to other objects. It is energy that has the potential to be converted into kinetic energy.
| 4 | |
| 2 | |
| 8 | |
| 24 |
Mechanical advantage (MA) can be calculated knowing only the distance the effort (blue arrow) moves and the distance the resistance (green box) moves. The equation is:
MA = \( \frac{E_d}{R_d} \)
where Ed is the effort distance and Rd is the resistance distance. For this problem, the equation becomes:
MA = \( \frac{3 ft.}{0.38 ft.} \) = 8
You might be wondering how having an effort distance of 8 times the resistance distance is an advantage. Remember the principle of moments. For a lever in equilibrium the effort torque equals the resistance torque. Because torque is force x distance, if the effort distance is 8 times the resistance distance, the effort force must be \( \frac{1}{8} \) the resistance force. You're trading moving 8 times the distance for only having to use \( \frac{1}{8} \) the force.
A a seesaw / teeter-totter is an example of which of the following?
third-class lever |
|
second-class lever |
|
first-class lever |
|
inclined plane |
A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.