| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.64 |
| Score | 0% | 53% |
Force of friction due to kinetic friction is __________ the force of friction due to static friction.
lower than |
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higher than |
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opposite |
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the same as |
The formula for force of friction (Ff) is the same whether kinetic or static friction applies: Ff = μFN. To distinguish between kinetic and static friction, μk and μs are often used in place of μ.
Which of the following statements about drag is false?
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 |
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drag occurs during movement through a fluid |
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slower objects experience more drag than faster objects |
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.
Which of the following statements about this pulley configuration is false?
Changes the direction of and multiplies the effort force |
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Mechanical advantage is the number of ropes that support the resistance |
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This is a block and tackle pulley configuration |
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Only multiplies the effort force |
A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.
What type of load varies with time or affects a structure that experiences a high degree of movement?
concentrated load |
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static load |
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impact 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.
| 0 | |
| 343.1 | |
| 300 | |
| 150 |