| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.60 |
| Score | 0% | 72% |
When all forces acting on a system cancel each other out, this is called:
rest |
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equilibrium |
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potential energy |
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stasis |
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.
Collinear forces:
are unrelated to each other |
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act in a common plane |
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pass through a common point |
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act along the same line of action |
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.
A watt is the unit for which of the following?
work |
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power |
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energy |
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mechanical advantage |
Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.
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 torque |
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decrease applied force |
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increase applied force |
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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).
| 10.5 | |
| 12 | |
| 9 | |
| 13.5 |
Mechanical advantage is resistance force divided by effort force:
MA = \( \frac{F_r}{F_e} \) = \( \frac{630 lbs.}{70 lbs.} \) = 9