Biomechanics Flashcards
What is Newton’s first law?
The law of inertia
Body continues at rest or constant velocity unless acted upon by a force
What is Newton’s second law?
The law of acceleration
When a force acts on object, rate of change of momentum experienced by object is proportionate to size of the force and takes place in direction force acts
What is Newton’s third Law?
For every action there is an equal and opposite reaction
What is linear motion? What is it caused by? Give examples
Movement of a body in a straight or curved line where all parts are moving in the same distance in the same direction over the same time.
Caused by direct force
E.G 100m Sprint/Swimmer
What is angular motion?What is it caused by? Give Examples
Movement of a body part in a circular path about an axis of rotation
Caused by an eccentric force (Outside centre of mass)
E.G Shoulder during cricket bowl, hip join kicking football
What is general motion? Give Examples
Combination of linear and angular motion
E.G Swimming, running,cycling
What is velocity? Give equation
Rate of change in displacement
Displacement/Time taken
What is acceleration? Give equation
Rate of Change in Velocity
(Final velocity-Initial Velocity)/Time taken
What is momentum? Give Equation
Quantity of motion possessed by a moving body
Mass x Velocity
Give Ways to increase Acceleration
Increase Force/Velocity/Speed
Increase Friction
Reduce Mass/Weight
Improve Technique
Decrease Air Resistance
Define Center of Mass (COM)
Point where mass of body tends to be concentrated and balanced in all directions
Where is COM in an item in which weight is evenly distributed?
The Middle
What 3 factors does the position of the COM depend on?
Body’s Position
Athletes body itself (Shape)
Gender
When might it be useful to move COM outside the body?
High Jump/ Fosbury Flop
Define Stability
The ability of the body to resist motion
Give Factors Affecting Stability
Mass Of Body
Size of base of support
Height of Centre of Mass
No of Points in contact with surface
Proximity of Line of gravity to centre of base of support
What is the line of gravity
Imaginary line extending from COM directly to ground
What 5 things can force do?
Create Motion
Accelerate a body
Decelerate a body
Change direction of a body
Change Shape of body
What is net force?
The overall force acting on a body
When are forces balanced?
When net force on the body = 0
When are forces Unbalanced?
When opposite forces acting on the body are unequal in size
What are two vertical forces?
Weight and Reaction Force
What are two Horizontal Forces?
Friction and Air resistance
What is friction?
The force that opposes the motion of 2 forces in contact
What is reaction force?
When there is a point of contact between two bodies there will always be a reactionary force
What is sliding friction?
When 2 surfaces have tendency to slide over one another
What is Directional Friction?
Acts in opposite direction to motion
What is parallel Friction?
Friction acts as parallel to the two surfaces in contact with each other
What factors affect friction?
Roughness/ Smoothness of surface
Roughness/Smoothness of footwear/object in contact with ground
Size of downforce
Temperature of surface (Dependent on characteristics of body in contact)