| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.03 |
| Score | 0% | 61% |
Which class of lever offers no mechanical advantage?
first |
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second |
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none of these, all levers offer mechanical advantage |
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third |
A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.
Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?
do the work in 3 minutes |
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do 100 ft. lb. of work in 4 minutes 12 seconds |
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do 25 ft. lb. of work in 2 minutes 5 seconds |
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do the work in 2 minutes |
Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.
| -3 | |
| 0.63 | |
| 5 | |
| 1.6 |
The mechanical advantage of a wheel and axle is the input radius divided by the output radius:
MA = \( \frac{r_i}{r_o} \)
In this case, the input radius (where the effort force is being applied) is 5 and the output radius (where the resistance is being applied) is 8 for a mechanical advantage of \( \frac{5}{8} \) = 0.63
Which of the following is the formula for torque?
τ = r/F |
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τ = rF |
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τ = F/r2 |
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τ = F/r |
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).
On Earth, acceleration due to gravity (g) is approximately __________.
1 m/s2 |
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6.67 x 10-11 m/s2 |
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9.8 m/s2 |
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1 m/s |
Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects: \(\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}\) . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s2.