week 7 biomechanics Flashcards
exam 2, revision
What is friction?
Friction is the force that arises whenever one body moves, or tends to move across the surface of another. Friction always opposes the motion or impending motion.
What are the types of friction?
The types of friction are: Static, Dynamic, and Rolling.
What is limiting (static) friction?
Limiting friction is the maximum frictional force that resists movement between two surfaces before sliding occurs.
What is the formula for limiting friction?
Fl = μl R
Fl - Limiting Friction, μl - Coefficient of Limiting Friction, R - Perpendicular Reaction Force
What factors affect the coefficient of friction?
The coefficient of friction depends on the material and roughness of the surfaces in contact.
What is sliding (dynamic) friction?
Sliding friction is the frictional force between two surfaces when there is movement between them.
What is the formula for sliding friction?
Fs = μs R
Fs - Sliding Friction, μs - Coefficient of Sliding Friction, R - Perpendicular Reaction Force
What happens to limiting and sliding friction when force increases?
The magnitude of limiting friction equals the force causing a body to slide until the upper limit is reached; sliding friction slightly decreases once movement starts.
What is rolling friction?
Rolling friction is the resistance encountered when an object rolls over a surface.
What influences rolling friction?
Rolling friction is influenced by weight, radius of the rolling object, surface deformability, and coefficient of friction.
How does friction affect spin on a ball?
Friction tends to impart spin on a ball, modifying the magnitude of friction based on the rate and direction of spin.
How can friction be increased to improve performance?
Friction can be increased by using studs, spikes, chalk on hands, sticky tape, and gloves.
How can friction be decreased to improve performance?
Friction can be decreased in activities like ice skating, roller skating, and bowling.
What happens during impacts?
When a ball hits a fixed surface, both the ball and surface compress slightly and then rebound as they strive to restore their original shape.
What is elasticity?
Elasticity is the property of a body that causes it to return to its original shape after being deformed.
What is the coefficient of restitution?
The coefficient of restitution is a measure of elasticity, calculated using the formula e = v / u.
What are direct impacts?
Direct impacts occur when bodies move straight towards each other or when one body is static and the other moves at right angles.
What are oblique impacts?
Oblique impacts occur when bodies do not collide head-on.
What is the biomechanical principle for injury prevention?
Use appropriate techniques and equipment to reduce injuries and optimize performance in tasks involving impacts.
How can forces during impacts be decreased?
Forces can be decreased by spreading the force over a longer time period.
What are examples of decreasing forces in sports?
Examples include landing techniques in gymnastics and equipment for cricket and baseball.
What are applications of energy absorption in sports?
Applications include running shoes, sprung floors for jumping, and sports equipment like horizontal/uneven bars.
