Kinematics & Kinetics Flashcards

1
Q

What is kinetics?

A

The study of the action of forces

The study of the motion with respect to time and forces

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2
Q

What are the types of general motion?

A

Linear motion

Angular motion

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3
Q

What is linear motion?

A

Motion along a line that may be curved or straight with all parts of the body moving in the SAME DIRECTION at the SAME SPEED

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4
Q

What is angular motion?

A

Motion that involves rotation around a central line or point

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5
Q

What are the types of linear motion?

A

Translation
Rectilinear
Curvilinear

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6
Q

Define “Translation”

A

PURE Linear motion

When a body experiences translation, it moves as a unit and portions of the body do not move relative to each other

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7
Q

Define “Rectilinear” motion

A

Motion along a straight line

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8
Q

Define “Curvilinear” motion

A

Motion along a curved line

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9
Q

In angular motion, what is the axis of rotation?

A

The imaginary line perpendicular to the plane of rotation and passing through the centre of rotation

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10
Q

What is general motion?

A

Motion that involves both linear and angular motion simultaneously

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11
Q

What are movements in the sagittal plane?

A
Elbow flexion/extension
Wrist flexion/extension
Finger flexion/extension
Knee flexion/extension
Ankle dorsi/plantar flexion
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12
Q

What are coronal plane movements?

A

ABduction & Adduction

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13
Q

What are transverse plane movements?

A

Medial rotation

Lateral rotation

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14
Q

Define speed, with equation.

A

Speed = distance covered with respect to time

Speed = distance % time

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15
Q

Define velocity with equation.

A

Velocity = time rate change of displacement
- velocity is the change of distance in a specific direction

Average velocity = displacement (distance in a direction) % time

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16
Q

Define acceleration with an equation.

A

Acceleration = the time rate of change of velocity
- Velocity varies therefore so does acceleration

Average Acceleration = change in velocity % change in time

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17
Q

What is a vector?

A

A vector is a quantity that has both MAGNITUDE and DIRECTION

Therefore both VELOCITY and ACCELERATION are vector quantities

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18
Q

What is vector resolution?

A

Vector resolution replaces a single vector with 2 perpendicular vectors so that the vector composition of the original vector yields the original vector

Solved using tip-to-toe method (forming right angled triangle)

Therefore solved using Pythagoras theorem
- c^2 = a^2 + b^2

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19
Q

What are the trigonometric solutions to vectors?

A

Sin(angle)= opposite % hypotenuse [SOH]

Cos(angle)= adjacent % hypotenuse [CAH]

Tan(angle)= opposite % adjacent [TOA]

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20
Q

What is angular distance?

A

The angle through which an object rotates from one position to another about an axis of rotation

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21
Q

What is angular displacement?

A

The smaller of two angles (with respect to a scale of 360degrees) between initial and final positions following a period of rotation

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22
Q

Define angular speed with an equation

A

Angular speed = the rate of change in angular distance

Average angular speed = angular distance % time taken to cover

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23
Q

Define angular velocity with an equation

A

Angular velocity = the rate of change of angular displacement

Average velocity = angular displacement % time

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24
Q

Define angular acceleration with equation

A

Angular acceleration = the rate of change of angular velocity

Average angular acceleration = change in angular velocity % time

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25
What is the unit of measurement in angles used in rotational movement?
Radians
26
Define radian
The length of an arc divided by its radius 1 radian = 360degrees % 2pie = 57.3 degrees
27
Define linear kinetics
The relationship between force and change in linear kinematics
28
Define angular kinetics
The relationship between force and change in angular kinematics
29
Define Inertia
Resistance of an object to action or to change Inertia is the tendency of a body to maintain its current state of motion, whether it is motionless or moving with a constant velocity It has no units of measurement
30
What is the mechanical definition of inertia
Resistance to acceleration
31
How is inertia related to mass?
The amount of inertia the 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 and the more difficult it is to disrupt that state
32
Define mass
The quantity of matter contained in an object Common unit kg Dependent on density and volume
33
Define force
A push or pull acting of a body- the product of mass and acceleration Each force is characterised by its magnitude, direction and point of application to a given body Measured in Newtons 1 N is the amount of force required to accelerate 1kg at 1m/s^2
34
What are the two types of force? Explain these types of force
Contact force - result from physical contact between objects eg collision - eg impulse - is the product of the magnitude and duration of a force Attraction force - forces that tend to attract objects towards each other - eg body weight = attraction du to gravity
35
Define momentum
The product of a mass of an object and its linear velocity
36
What are Newtons 3 laws?
First law = law of inertia Second Law = law of acceleration Third Law = law of reaction
37
What is Newtons First Law of inertia?
A body remains at rest or in a state of constant motion in a straight line unless it is acted upon by an applied force The state of motion is described by the body's momentum (p), defined as the product of its mass and linear velocity P=MV If no force is applied to a body, it's momentum will remain constant
38
Define Newtons Second Law of acceleration
- The time rate of change of the linear momentum of a body is equal to the force applied to it - Force will cause the body to accelerate in direct proportion to the magnitude of the force and the same direction of the force - Describes how a rigid body moves when external forces are applied to it
39
What is the equation of Newtons Second law of acceleration?
F=ma Can also be a = f%m (When a force acts on an object, acceleration is inversely proportional to the objects mass and directly proportional to the magnitude of the force)
40
Define Newtons Third Law of reaction
When one body applies a force to another, the second body responds with an equal and opposite reaction force to the first body
41
What is Newtons Law of gravitation states
Force is directly proportional to the product of the masses of the two objects and inversely proportional to the square of the distance between the two objects Bodyweight is the product of mass and acceleration due to gravity
42
What is a centre of gravity?
- A body's centre of gravity is the point around which the body's weight is equally balanced, no matter how the body is positioned - It is the point of which the line of action of the weight of an object acts irrespective of the position of the object - From a kinetic perspective, the location of the centre of mass determines the way in which the body responds to external forces
43
What is Centric force?
When force is applied through the centre of a body and then the body will be translated in the direction of the applied force
44
What is eccentric force?
If a force is applied through a point other than the centre of the body, the body will undergo both translation and rotation
45
What is the rotary effect created by eccentric force?
Torque
46
What is torque?
Rotary effect created by eccentric force It is the angular equivalent of linear force Torque is the product of force (F) and the perpendicular distance (d) T=Fd The greater the amount of torque acting at the axis of rotation, the greater the tendency for rotation to occur
47
Define a lever
A lever is a rigid free bar which is free to rotate around a fixed pint called the FULCRUM The position of the fulcrum is fixed so that it is not free to move with respect to the bar Levers are used to lift loads in an advantageous way and to transfer movement from one point to another
48
What are the 3 classes of lever?
1. The fulcrum located between the applied force and the load 2. The fulcrum is at one end, the force is at the other end and the load is in between 3. The fulcrum is at one end, the load is at the other end and the force is in between
49
What is a free body diagram?
A sketch that shows a defined system in isolation with all of the force vectors acting on the system Means of presenting the forces, moments of force and geometry of mechanical systems
50
What are the steps in solving mechanics problems?
Step 1 = free body diagram Step 2 = use the free body diagram to derive the equations of motion of the object Step 3 = know the numerical values are submitted and equations are solved for the unknown terms
51
How do you construct a free body diagram?
- draw object of interest in minimalist form - write out the coordinates of the object to specify its position - indicate the objects centre of mass with a marker; draw accelerations from here - draw and label all external reaction forces, basing directions on how the object experiences them - draw all Unknown forces and moments with positive coordinate system, Unknown forces must be applied wherever the body is in contact with the environment or other bodies - draw and label global coordinate system axes off to the side of the diagram indicating which are the positive directions
52
Define compression as a mechanical load on the human body
- Compressive force can be thought of as a squeezing force | - the amount a tissue can tolerate without rupture
53
Define tension as a mechanical load on the human body
- tension is the opposite of compressive force - tensile force - tensile force is a pulling force that creates tension in the object to which it is applied - muscles produce tensile force that pulls on the attached bones -
54
What is Youngs Modulus?
It is the ratio of stress to strain
55
What is Hookes Law?
It is as stress increases, strain increases in proportion to it
56
Define Shear as a mechanical load on the human body
- Shear force acts parallel or tangent to a surface - Shear force tends to cause one portion of the object to slide, displace or shear with respect to another portion of the object
57
Define mechanical stress as a load on the human body
Stress = the distribution of force within a body, quantified as force divided by the area over which the force acts Pressure represents the distribution of force external to a solid body, STRESS, represents the resulting force distribution inside a solid body when an external force acts
58
Define bending as a mechanical load on the human body
Asymmetric loading that produces tension on one side of a body's longitudinal axis and compression on the other side Common in vertebral disc injury
59
Define torsion as a mechanical load on the human body
TORSION occurs when a structure is caused to twist about its longitudinal axis, typically when one end of the structure is fixed TORSION is load producing twisting of a body around its longitudinal axis Torsional fractures of the tibia are common in football and skiing
60
What is it called when more than one mechanical load is applied to the human body?
Combined loading
61
What is kinematics?
- The study of motion | - without reference to force