| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.89 |
| Score | 0% | 58% |
A wedge converts force applied to its blunt end into force __________ its inclined surface.
along |
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opposite to |
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parallel to |
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perpendicular to |
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.
A fixed pulley is useful for which of the following?
changing the direction of the output force |
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multiplying the input distance |
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changing the direction of the input force |
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multiplying the input force |
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.
What type of load varies with time or affects a structure that experiences a high degree of movement?
dynamic load |
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impact load |
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static load |
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concentrated load |
A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.
Assuming force applied remains constant, which of the following will result in more work being done?
increasing the coefficient of friction |
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moving the object with more acceleration |
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moving the object with more speed |
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moving the object farther |
Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done.
| 35 ft. | |
| 0 ft. | |
| 2.1 ft. | |
| 0.7 ft. |
To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:
Rada = Rbdb
where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.Solving for db, our missing value, and plugging in our variables yields:
db = \( \frac{R_ad_a}{R_b} \) = \( \frac{35 lbs. \times 1 ft.}{50 lbs.} \) = \( \frac{35 ft⋅lb}{50 lbs.} \) = 0.7 ft.