| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.97 |
| Score | 0% | 59% |
Which of the following represents the force a surface exerts when an object presses against it?
mass |
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friction |
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normal force |
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counter force |
Normal force (FN) represents the force a surface exerts when an object presses against it.
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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Lisa |
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They have done an equal amount of work |
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Sam |
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.
Which of the following will increase the mechanical advantage of this inclined plane?
lengthen the ramp |
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shorten the ramp |
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lower the force acting at the blue arrow |
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increase the force acting at the blue arrow |
The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.
What is the first step to solving a problem where multiple forces are acting on an object?
calculate the net force |
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calculate potential energy |
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calculate kinetic energy |
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calculate the total force |
In mechanics, multiple forces are often acting on a particular object and, taken together, produce the net force acting on that object. Like force, net force is a vector quantity in that it has magnitude and direction.
When all forces acting on a system cancel each other out, this is called:
equilibrium |
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stasis |
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potential energy |
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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.