| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.22 |
| Score | 0% | 64% |
A fixed pulley is useful for which of the following?
multiplying the input force |
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changing the direction of the input force |
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changing the direction of the output force |
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multiplying the input distance |
A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.
| 9 | |
| 11 | |
| 12 | |
| 8 |
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 = \( \frac{d_e}{d_r} \) = \( \frac{45 ft.}{5 ft.} \) = 9
Which of the following is not a type of structural load?
live load |
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occupancy load |
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dead load |
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wind load |
Dead load is the weight of the building and materials, live load is additional weight due to occupancy or use, snow load is the weight of accumulated snow on a structure and wind load is the force of wind pressures against structure surfaces.
A wedge converts force applied to its blunt end into force __________ its inclined surface.
opposite to |
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parallel to |
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perpendicular to |
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along |
The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.
When all forces acting on a system cancel each other out, this is called:
stasis |
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potential energy |
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equilibrium |
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rest |
When a system is stable or balanced (equilibrium) all forces acting on the system cancel each other out. In the case of torque, equilibrium means that the sum of the anticlockwise moments about a center of rotation equal the sum of the clockwise moments.