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76 Cards in this Set
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Biomechanics

The study of the mechanical aspects of living organisms.


Problems that biomechanics can be used to solve

How can sporting equipment or sports techniques be altered to enhance performance?
How can sporting equipment or sports techniques be altered to prevent or reduce injuries? Does stretching before running help or hinder performance? What lifting kinematics can minimize the stress of lifting? 

Qualitative analysis versus Quantitative analysis

A qualitative analysis pertains to quality without the use of numbers while a quantitative analysis involves numbers.


Kinematics versus kinetics

Kinetics is the study of forces while kinematics is the study of appearance of motion.


Types of equipment used to perform a kinematic analysis

Timing devices (stopwatch), velocity measuring systems (radar gun), optical imaging systems (video cameras), accelerometers, inertial measurement units, motion capture systems


Types of equipment used to perform a kinetic analysis

Force platforms, pressure sensors, electromyography


Vector

Has magnitude and direction


Scalar

Has magnitude


If given the right angle components of a vector, how would you find its magnitude?

By finding the hypotenuse of the right triangle formed by the axes.


Units of displacement, is it a vector or scalar

Meters, vector


Units of distance, is it a vector or scalar

Meters, scalar


Units of velocity, is it a vector or scalar

Meters per second, vector


Units of speed, is it a vector or scalar

Meters per second, scalar


Units of force, is it a vector or scalar

Newtons, vector


Units of acceleration, is it a vector or scalar

Meters per second squared, vector


Units of mass, is it a vector or scalar

Grams, scalar


Units of time, is it a vector or scalar

Seconds, scalar


Three cardinal planes and examples of movement in each

Sagittal  forward and backward movements, such as marching, bowling, or cycling
Frontal  lateral movements such as cartwheels, side kicks, side steps, or jumping jacks Transverse  rotational movements such as a dancer's piroutte 

Flexion

Occurs when a position made from the joint angle is decreasing, such as an elbow being flexed when the hand is brought to the shoulder.


Extension

Occurs when a joint angle is increased along the same plane, such as the straightening of a leg


Hyperextension

Occurs when the extension is beyond 180 degrees, such as when the neck is hyperextended when one looks up to the ceiling


Dorsiflexion

Occurs when the angle between the dorsum or foot and the leg are decreased so the toes are brought closer to the shin.


Plantarflexion

Occurs when movement increases the 90 degree angle between the front of the foot and the shin, such as standing on your tip toes


Abduction

Draws the limb away from the medial sagittal plane of the body


Adduction

Brings a part of the anatomy closer to the middle sagittal plane of the body


Mass

A quantity of matter that composes a body


Inertia

Resistance to change in a state of motion


How are inertia and mass related

The amount of inertia a body possesses is directly proportional to its mass. The more massive an object is, the more it tends to maintain its current state of motion.


Force

A push or pull characterized by magnitude, direction, and point of application


Units of force

Newtons


What is a net force?

The single resultant force derived from the vector composition of two or more forces.


Why do we find the net force acting on a body?

A force rarely acts in isolation, it is important to recognize the overall effect from many forces


Center of gravity

The point at which a body's weight is equally balanced no matter how the body is positioned.


Weight

The gravitational force exerted on a body


Stress versus pressure

Pressure and stress are the force per unit of area over which a force acts. Pressure is the distribution of force external to a solid body while stress represents the resulting force distribution inside a solid body.


Compression

A pressing or squeezing force directed axially through a body


Tension

A pulling or stretching force directed axially through a body


Distance versus displacement

Distance is measured along the path of motion while displacement is a change in the location from the directed distance to the initial location.


Speed versus velocity

Speed is the distance covered over the time taken to cover it, while velocity is the rate of change in position or location


Acceleration

The rate of change in linear velocity


What happens if the acceleration vector is in the opposite direction of the velocity vector?

The object is slowing down


What happens if the acceleration vector is in the same direction of the velocity vector?

The object is speeding up


Acceleration due to gravity

9.81m/s^2


Projectile motion

A body in free fall that is subject to only the forces of gravity and air resistance


How do the equations for the horizontal and vertical components of projectile motion differ?

The vertical component is influenced by gravity while the horizontal component is not.


Angular distance

The sum of all angular changes undergone by a rotating body


Angular displacement

The change in angular position from initial to final position


Angular speed

A scalar measure of rotational rate


Angular velocity

The change in angular position


Angular acceleration

The rate of change in angular velocity


Units of angular displacement

Degrees, radians, or rotations/revolutions


Units of angular velocity

Degrees/seconds or radians/seconds


Units of angular acceleration

Degrees/seconds^2 or radians/seconds^2


Newtons laws

1st law  Law of inertia  a body will maintain a state or rest or constant velocity unless acted on by an external force
2nd law  Law of acceleration  a force applied to a body causes acceleration of that body 3rd law  Law of reaction  every action has an equal and opposite reaction 

Reaction force

Acts in the opposite direction to an action forcr


Ground reaction force

Any force exerted on the ground on a body in contact with it


Momentum

Quantity of motion moving along a body


Equation for momentum

M = mv


Principle of conservation of momentum

States that in the absence of external forces, the total momentum of a given system remains constant.


Equation of principle of conservation of momentum

M1 = M2 or (MV)1 = (MV)2


Impulse

The product of a force and the time interval over which a force acts


How are impulse and momentum related?

Because impulse causes momentum


Mechanical work

Product of a force applied against a resistance and the displacement of the resistance in the friction of the force.


Equation of mechanical work and units

W=Fd, Joules


Energy

The ability to do work


How are work and energy related?

Objects that have greater energy can do more work


Equations for potential and kinetic energy

Potential = PE = (wt)(ht)
Kinetic = KE = 1/2mv^2 

The peak of a ball's kinetc energy when thrown upwards

Zero


The instant impact of a ball's kinetic energy after being thrown upward

9.8


Static equilibrium

A motionless state in which there is no net force or net torque acting


Base of support

The area bound by the outermost regions of contact between a body and its support surface


How to increase a body's stability

Increasing body mass and friction between the body and surfaces of contact


Moment of inertia

Inertial property for rotating bodies


How does distributing the mass farther from the axis of rotation affect moment of inertia?

Distributing the mass farther from the axis of rotation makes it more difficult to swing an object


Angular momentum

The quantity of angular motion possessed by a body


Principle of conservation of angular momentum

Total angular momentum of a given system remains constant in the absence of external torques
