| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.90 |
| Score | 0% | 78% |
Two or more pulleys used together are called:
gears |
|
third-class lever |
|
block and tackle |
|
wheel and axle |
Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.
On Earth, acceleration due to gravity (g) is approximately __________.
1 m/s |
|
6.67 x 10-11 m/s2 |
|
9.8 m/s2 |
|
1 m/s2 |
Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects: \(\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}\) . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s2.
An object's resistance to changes in direction is known as:
kinetic energy |
|
mass |
|
inertia |
|
weight |
The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.
| 20 ft⋅lb | |
| 5 ft⋅lb | |
| 0 ft⋅lb | |
| 2 ft⋅lb |
| 1.4 | |
| 1.5 | |
| 0.5 | |
| 5.5 |
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 = \( \frac{N_1}{N_2} \) = \( \frac{24}{16} \) = 1.5