| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.01 |
| Score | 0% | 60% |
What type of load is sudden and for a relatively short duration?
impact load |
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dynamic load |
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concentrated load |
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non-uniformly distributed load |
A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.
Which of these is the formula for kinetic energy?
\(KE = {1 \over 2}mh^2\) |
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\(KE = {1 \over 2}mv^2\) |
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\(KE = {m \over v^2 }\) |
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\(KE = mgh\) |
Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.
| 64.7 lbs. | |
| 21.6 lbs. | |
| 46.1 lbs. | |
| 43.1 lbs. |
This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:
Fede = Frdr
Plugging in the variables from this problem yields:
Fe x 16 ft. = 230 lbs. x 3 ft.
Fe = \( \frac{690 ft⋅lb}{16 ft.} \) = 43.1 lbs.
Which of the following statements about drag is false?
slower objects experience more drag than faster objects |
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drag occurs during movement through a fluid |
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the amount of drag depends on the speed of an object |
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the amount of drag depends on the shape of an object |
Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.
| 10.4 psi | |
| 34.7 psi | |
| 13.6 psi | |
| 11.6 psi |
According to Boyle's Law, pressure and volume are inversely proportional:
\( \frac{P_1}{P_2} \) = \( \frac{V_2}{V_1} \)
In this problem, V2 = 35 ft.3, V1 = 45 ft.3 and P1 = 9.0 psi. Solving for P2:
P2 = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{9.0 psi}{\frac{35 ft.^3}{45 ft.^3}} \) = 11.6 psi