| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.19 |
| Score | 0% | 64% |
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?
Sam |
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Neither have done any work |
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Lisa |
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They have done an equal amount of work |
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.
Two gears are connected and the larger gear drives the smaller gear. The speed of rotation will __________ and the torque will __________.
increase, decrease |
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decrease, increase |
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decrease, decrease |
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increase, increase |
Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.
Coplanar forces:
act in a common plane |
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have opposite dimensions |
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act along the same line of action |
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pass through a common point |
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.
Tension is a force that does which of the following?
stretches an object |
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compacts an object |
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heats up an object |
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slows an object |
Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.
The force exerted on an object due to gravity is called:
density |
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potential energy |
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weight |
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mass |
Mass is an intrinsic property of matter and does not vary. Weight is the force exerted on the mass of an object due to gravity and a specific case of Newton's Second Law of Motion. Replace force with weight and acceleration with acceleration due to gravity on Earth (g) and the result is the formula for weight: W = mg or, substituting for g, weight equals mass multiplied by 9.8 m/s2.