Flashcards
Lecture 9a - Forces Opposing Motion
Cards in this deck (17)
- 1What are the forces opposing motion?* Air resistance;
- fluid environment
- velocity of motion
* Gravity - 2Define frictionforce that occurs when an object moves or tends to move while in contact with another object
- 3What are the 2 types of dynamic friction?Sliding friction and rolling friction
N.B. there is also static friction - 4What is limiting friction?the frictional force required to overcome inertia.
for two dry surface, the limiting friction is equal to the normal reaction multiplied by a constant, the value of this constant depending on the nature of the surfaces - 5What is the equation for friction?F = μR
F = friction force
μ= coefficient of friction
R = reaction force (normal) - 6What does the coefficient of friction depend on?The nature of the two surfaces;
- hardness
- surface texture (degree of roughness)
μ= 0 perfectly smooth/frictionless - 7True or False; For dry, unlubricated surfaces less frictional force exists between rough-textured surfaces than smooth surfacesFALSE
For dry, unlubricated surfaces MORE frictional force exists between rough-textured surfaces than smooth surfaces - 8True or False; For dry, unlubricated surfaces the greater the force pressing the surfaces together the greater is the resistance to slidingTRUE
- 9How can you optimise friction during exercise?increase or decrease friction by altering surfaces or interposing substances between contacting surfaces
- 10When you adjust friction what happens to body lean and friction?normal force changes
- 11When you adjust friction what happens to friction and wet surfaces?technique changes
- 12What happens in the human body if friction is too high?increased heat production and damage/wear to tissues
- 13How is friction decreased in the human body?- synovial fluid
- smooth articular surfaces
- synovial sheaths surrounding tendons
- bursae and blisters - 14Define rolling frictionresistive force created when a spherical object rolls across a surface
- 15What does rolling friction depend on?- nature of sphere & surfaces involved
- normal force between the two bodies
- diameter of the sphere - 16List in order of least to most rolling frictiona < b < c
c has the most rolling friction
a has the least rolling friction - 17list in order of greatest friction; rolling friction, static friction, and sliding frictionstatic > sliding > rolling
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- MEDI222 - Biomechanics (Lecture Notes) Flashcards on Lecture 9a - Forces Opposing Motion, created by Nicole Chadwick on 13/06/2018.
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- Nicole Chadwick
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