| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.80 |
| Score | 0% | 56% |
Which of the following is the formula for gravitational potential energy?
\(PE = { 1 \over 2} mv^2\) |
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\(PE = { 1 \over 2} mg^2\) |
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\(PE = mgh\) |
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\(PE = mg^2h\) |
Gravitational potential energy is energy by virtue of gravity. The higher an object is raised above a surface the greater the distance it must fall to reach that surface and the more velocity it will build as it falls. For gravitational potential energy, PE = mgh where m is mass (kilograms), h is height (meters), and g is acceleration due to gravity which is a constant (9.8 m/s2).
Normal force is generally equal to the __________ of an object.
density |
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coefficient of friction |
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mass |
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weight |
Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.
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 25 ft. lb. of work in 2 minutes 5 seconds |
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do 100 ft. lb. of work in 4 minutes 12 seconds |
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do the work in 2 minutes |
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do the work in 3 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.
Which of the following represents the force a surface exerts when an object presses against it?
mass |
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friction |
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counter force |
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normal force |
Normal force (FN) represents the force a surface exerts when an object presses against it.
Which of the following is not a modulus of elasticity?
stretch modulus |
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shear modulus |
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bulk modulus |
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stress modulus |
The modulus of elasticity measures how much a material or structure will deflect under stress. Stretch modulus is longitudinal stretch (like stretching raw bread dough), shear modulus is longitudinal deflection (like the horizontal displacement of a stack of magzines when a heavy object is placed upon them), and bulk modulus is compression of volume (like the compression of a loaf of bread under a heavy can at the bottom of a grocery bag).