| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.11 |
| Score | 0% | 62% |
Connected gears of different numbers of teeth are used together to change which of the following charasteristics of the input force?
rotational direction |
|
energy |
|
force |
|
torque |
Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.
Collinear forces:
are unrelated to each other |
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pass through a common point |
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act in a common plane |
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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.
| 187.5 lbs. | |
| 62.5 lbs. | |
| 0 lbs. | |
| 20.83 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 Ra, our missing value, and plugging in our variables yields:
Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{50 lbs. \times 5 ft.}{4 ft.} \) = \( \frac{250 ft⋅lb}{4 ft.} \) = 62.5 lbs.
Which of the following is not a characteristic of a ceramic?
low corrosive action |
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high melting point |
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chemically stable |
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low density |
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.
A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?
tension is equal in all parts of the rope |
|
near the car |
|
near the truck |
|
in the middle |
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.