KIN 215 Midterm PDF

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215 Midterm

1. Define: biomechanics, kinematics, kinetics, mechanics

Biomechanics- the study of human movement using principles of physics and math Kinematics- study of motion without considering what is causing the motion Kinetics- the study of forces acting on mechanisms Mechanics- studies the motions of everyday objects that you can see -

Based on the work of Sir Isaac Newton

2. List the four parts that are used for a symbol in your text

Leading superscript- direction (X or Y) Following superscript- time point Following subscript- the object you’re talking about

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3. Explain why you should study biomechanics -

To enhance skill performance Lower injury risk Understand how living bodies can move

4. Explain how understanding biomechanics can achieve this purpose Through biomechanics we can answer questions such as What is the most efficient, or effective way to do a particular work task? what mode of exercise is the best for producing increased power performance?

5. Describe the three sets of principles that are used in biomechanics

Multisegmental- the body is not a single element -

It’s composed of connected segments

Biological- humans are animate and not machines -

Biological principles always influence the mechanics analyzed

Mechanical- study of forces and their effects -

-

Dynamics - Kinematics- describing motion without caring what causes it - Kinetics- studying forces of motion Statics- no acceleration

6. Explain the difference between kinematics and kinetics - Kinematics- describing motion without caring what causes it - Kinetics- studying forces of motion

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1. Define: acceleration, displacement, distance, position, scalar, slope, speed, vector, velocity

Acceleration- how quickly something is speeding up or slowing down Displacement- Δ position (p) - vector quality (direction and magnitude - p1 (final) – p (initial) = Δ position Distance- how far a body has traveled - scalar quantity Position- object’s location in the frame of reference Scalar- a quantity; only having magnitude and not direction Slope- Δ y / Δ x = Δ velocity / Δ time Speed- how fast a body is moving with no regard to direction - distance / Δ time Vector- quantity; includes magnitude and direction Velocity- how fast a body is moving in a particular direction - Δp / Δt

2. Explain the difference between speed and velocity

Speed- how fast a body is moving with no regard to direction -

Scalar quantity

Velocity- how fast a body is moving in a particular direction -

vector quantity

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3. Recognize equations for: distance, displacement, speed, velocity, acceleration Distance- (d) Displacement- Δp = p 1 – p Speed- d / Δ t Velocity- Δ p / Δ t Acceleration/ rate of acceleration- Δ v / Δ t

4. Identify speed and velocity on a position-time curve Speed- d / Δ t Velocity- Δ p / Δ t

5. Identify acceleration on a velocity-time curve Acceleration- Δ v / Δ t

6. Describe situations where velocity is more important than acceleration, and vice versa (-) Velocity tells you movement in the (-) direction The sign doesn’t determine direction with acceleration, it tells you if someone is speeding up or slowing down

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1. Define: cadence, gait, step, stride Cadence- number of steps in a given time Gait- a person’s manner of walking Step- initial contact of one foot to initial contact of the other foot Stride- initial contact of one foot to initial contact of the same foot

2. List the determinants of gait velocity Gait velocity -

step length step rate

Gait Speed= length / step x steps / minute

3. Define: components, resultant Components- parts of a resultant vector; two or more vectors that are acting in different directions Resultant- a vector that is equivalent to the combined effect of two or more vectors

4. Given a resultant magnitude and direction, determine the components in the x and y directions

1. 2. 3. 4.

locate an origin (where motion starts) define an axis (always horizontal and vertical) specify positive and negative direction use SOH CAH TOA or c ² = a ² + b ²

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1. Describe the characteristics of a gait cycle Gait cycle- one leg at a time -

initial contact of one foot to contact of the same foot

Stance phase – 60% - contact with ground Initial contact, foot flat, mid stance, push off Swing phase- 40% - not in contact with ground Acceleration, mid swing, deceleration

1. Define: projectile, range, relative height, trajectory Projectile- any airborne body that is only subjected to gravity and wind resistance after it has left the ground Range- the horizontal displacement of a projectile Relative height- the difference between the vertical position at takeoff and the vertical position at landing Trajectory- the path of a projectile

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2. Recognize and be able to use the equation for the range of a projectile that takes off and lands at the same height

3. List the determinants of a projectile’s trajectory  



The velocity at take off The angle of take off Relative height

4. Describe situations where a larger release angle is more advantageous For a dancer to increase flight time

5. Describe situations where a smaller release angle is more advantageous

Quarterback passing to a receiver Dancer wanting to decrease flight time

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1. Define: Osteokinematics- motion of bones Arthrokinematics- motion at the joint surfaces

2. Know the names and locations of select bones and muscles

3. Describe the clinical reference frame Sagittal plane- divides medial/lateral AOR: medial-lateral Transverse plane- divides superior/inferior AOR: superior-inferior Frontal plane- divides anterior/posterior AOR: anterior-posterior

When movement occurs in a plane, the direction of movement is parallel to the plane

4. Determine on which plane, and about which axis, different joint motions typically occur

Sagittal plane- divides medial/lateral AOR: medial-lateral Flexion and extension Transverse plane- divides superior/inferior AOR: superior-inferior Rotational movements Frontal plane- divides anterior/posterior AOR: anterior-posterior Abduction and adduction

5. List the features of a synovial joint

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Joint capsule Articular cartilage A joint cavity filled with synovial fluid A synovial membrane lining the joint capsule Accessory structures Sensory nerves and blood vessels

6. List the six types of synovial joints and the motions associated with each - Gliding- 0 rotational DOF, no AOR ex. carpals - Hinge- 1 rotational DOF, 1 AOR ex. ankle, elbow - Pivot- 1 rotational DOF, 1 AOR ex. proximal radioulnar joint - Condyloid- 2 DOF, 2 AOR ex. knee - convex surface in both directions - Saddle- 2 DOF, 2 AOR ex. first carpometacarpal - one bone has convex and concave in other direction - Spherical (ball and socket)- 3 DOF, 0 AOR ex. hip, shoulder

7. Describe the following types of arthrokinematic motion: sliding/gliding, spinning, rolling

Sliding/ gliding- pure linear movement (translation) Spinning- pure rotation Rolling- combination of translation and rotation

8. Define joint stability and joint flexibility, and explain what each is determined by Joint stability- ability of a joint to resist abnormal displacement of the articulating bone - influenced by supporting structures, suction between articular surfaces

215 Midterm

Joint flexibility- description of the relative ranges of motion allowed at a joint in different directions - influenced by tension in joint capsule and ligaments, soft tissue bulk

9. Describe movement using proper anatomical terms

1. Define: rigid body, axis of rotation, angular position, angular displacement, angular velocity, angular acceleration

Rigid body- a body that maintains a constant shape - has length, but not height and width - ex. a baseball bat, long bones

Axis of rotation- an origin - on humans its our joints - direction: negative- clockwise; positive- counterclockwise

Angular position Ɵ- the orientation of a rigid body in reference to some axis - can be measured in degrees or radians

Angular displacement ∆Ɵ- the change in orientation of a rigid body in reference to some axis - Change in angular position between two time periods of interest - Δθ =θ""−θ"

Angular velocity- how fast a body is rotating in a particular direction - ω= Δθ / Δt

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Angular acceleration- how quickly a body is speeding up or slowing down its rotation in a particular direction - α= Δ ω / Δt

3. Identify angular velocity on an angular position-time curve

Velocity is the slope of the position-time curve • Steeper slope = greater velocity • When the slope is negative, the velocity is negative • A change from a positive direction to a negative direction will require the velocity to be zero in the transition

4. Identify angular acceleration on an angular velocity-time curve

Acceleration is the slope of the velocity- time curve • Speeding up in the positive direction and slowing down in the negative direction both produce positive acceleration! • If a rotating body does not change it’s angular velocity (starts and ends with the same angular velocity) then the change in acceleration is zero, and the areas under the positive and negative acceleration-time curves will cancel.

215 Midterm

5. Given angular displacement and time data, calculate angular velocity and angular acceleration

6. Convert angular velocity to linear velocity V = lr ×ω The linear velocity of a point on a rotating body is determined by: • Angular velocity of the rigid body • Distance from the axis of rotation on the body

7. Convert angular acceleration to tangential and centripetal acceleration • For each angular velocity, there are two linear accelerations to consider: • Tangential • Change in magnitude of the linear velocity tan - a = lr α • Centripetal • Change in direction of the linear velocity - centripetal a= l r ω2...