| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.02 |
| Score | 0% | 60% |
Coplanar forces:
have opposite dimensions |
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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.
A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?
near the truck |
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tension is equal in all parts of the rope |
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in the middle |
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near the car |
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.
What type of load is sudden and for a relatively short duration?
impact load |
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non-uniformly distributed load |
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concentrated load |
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dynamic 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.
| 80 lbs. | |
| 60 lbs. | |
| 240 lbs. | |
| 30 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 = \( \frac{R_ad_a}{d_b} \) = \( \frac{40 lbs. \times 3 ft.}{2 ft.} \) = \( \frac{120 ft⋅lb}{2 ft.} \) = 60 lbs.
What type of load creates different stresses at different locations on a structure?
impact load |
|
dynamic load |
|
non-uniformly distributed load |
|
static 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.