| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.14 |
| Score | 0% | 63% |
Which of the following will increase the mechanical advantage of a second-class lever?
move the object being lifted closer to the fulcrum |
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move the fulcrum between the force and the object being lifted |
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move the object being lifted farther away from the fulcrum |
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decrease the length of the lever |
A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.
Assuming force applied remains constant, which of the following will result in more work being done?
moving the object farther |
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increasing the coefficient of friction |
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moving the object with more speed |
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moving the object with more acceleration |
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.
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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Lisa |
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They have done an equal amount of work |
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Neither have done any 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.
An object's resistance to changes in direction is known as:
mass |
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inertia |
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kinetic energy |
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weight |
The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.
When it comes to force, mass and acceleration have what kind of relationship?
logarithmic |
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exponential |
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linear |
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inverse |
Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.