| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.25 |
| Score | 0% | 65% |
| 45 lbs. | |
| 30 lbs. | |
| 360 lbs. | |
| 90 lbs. |
To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:
Rada = Rbdb
where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.Solving for Rb, our missing value, and plugging in our variables yields:
Rb = \( \frac{R_ad_a}{d_b} \) = \( \frac{60 lbs. \times 3 ft.}{2 ft.} \) = \( \frac{180 ft⋅lb}{2 ft.} \) = 90 lbs.
Which of the following is not a characteristic of a ceramic?
low density |
|
chemically stable |
|
high melting point |
|
low corrosive action |
Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.
Tension is a force that does which of the following?
slows an object |
|
stretches an object |
|
heats up an object |
|
compacts an object |
Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.
Assuming force applied remains constant, which of the following will result in more work being done?
moving the object farther |
|
moving the object with more speed |
|
increasing the coefficient of friction |
|
moving the object with more acceleration |
Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done.
| 171 ft⋅lb | |
| 0 ft⋅lb | |
| 361 ft⋅lb | |
| None of these is correct |