| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.31 |
| Score | 0% | 66% |
Coplanar forces:
have opposite dimensions |
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act in a common plane |
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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.
The mass of an object correlates to the size of the object but ultimately depends on:
the object's potential energy |
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the object's weight |
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gravity |
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the object's density |
Mass is a measure of the amount of matter in an object. In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.
Torque involves a perpendicular force applied to a lever arm that moves around a center of rotation. Increasing the length of the lever arm will do which of the following?
decrease applied force |
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increase applied force |
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decrease torque |
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increase torque |
Torque measures force applied during rotation: τ = rF. Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).
The force amplification achieved by using a tool, mechanical device or machine system is called:
efficiency |
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power |
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mechanical advantage |
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work |
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.
A a seesaw / teeter-totter is an example of which of the following?
inclined plane |
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first-class lever |
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second-class lever |
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third-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.