| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.18 |
| Score | 0% | 64% |
| 8.2 lbs. | |
| 16.4 lbs. | |
| 14.8 lbs. | |
| 17.9 lbs. |
This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:
Fede = Frdr
Plugging in the variables from this problem yields:
Fe x 14 ft. = 230 lbs. x 1 ft.
Fe = \( \frac{230 ft⋅lb}{14 ft.} \) = 16.4 lbs.
Which of the following is not a type of bridge?
truss |
|
block |
|
arch |
|
cable |
The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.
A watt is the unit for which of the following?
energy |
|
mechanical advantage |
|
power |
|
work |
Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.
The principle of moments defines equilibrium in terms of:
torque |
|
energy |
|
speed |
|
power |
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.
What defines the mechanical advantage of a first class lever?
input force |
|
output distance |
|
output force |
|
position of the fulcrum |
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.