| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.05 |
| Score | 0% | 61% |
Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?
Neither have done any work |
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They have done an equal amount of work |
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Sam |
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Lisa |
Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.
The science that deals with motion and the forces that produce motion is called which of the following?
mechanics |
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physics |
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engineering |
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aeronautics |
Mechanics deals with motion and the forces that produce motion.
A a seesaw / teeter-totter is an example of which of the following?
first-class lever |
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third-class lever |
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inclined plane |
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second-class lever |
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.
The standard unit of energy is the:
Watt |
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Joule |
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Horsepower |
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Volt |
The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).
What type of load doesn't create specific stress points or vary with time?
static uniformly distributed load |
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non-uniformly distributed load |
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impact 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.