KIN 3309 1st Edition Lecture 23 Outline of Last Lecture I. Electromyography (EMG)II. Accelerometers/IMUOutline of Current Lecture I. Kinematics vs. KineticsII. Vectors and ScalarsIII. Linear vs. Angular MotionIV. Position and DisplacementV. Important ParametersVI. What is a Projectile?VII. Two DimensionsVIII. Types of AnglesIX. Angular and Linear PositionX. Angular and Linear VelocityXI. Centripetal (Radial) AccelerationXII. Sources of Forces Affecting Human MovementXIII. ForceXIV. Center of MassXV. WeightXVI. Types of ForcesXVII. TorqueXVIII. Newton’s Laws of MotionXIX. Free Body DiagramsXX. MomentumXXI. Moment of InertiaXXII. Radius of GyrationXXIII. Conservation of MomentumXXIV. Linear ImpulseXXV. Angular ImpulseXXVI. Linear WorkXXVII. Angular WorkXXVIII. Linear PowerXXIX. Angular PowerXXX. Linear EnergyThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.XXXI. Angular EnergyXXXII. Work-Energy TheoremXXXIII. Conservation of EnergyCurrent LectureI. Kinematics vs. Kineticsa. Kinematicsi. Examines spatial (space) and temporal (time) characteristics of motion1. Position (displacement), velocity, and accelerationii. The forces causing the motion are not consideredb. Kineticsi. Deals with the cause of motion – forceii. The concept of force is the basis for understanding linear kineticsiii. Linear kinetics – deals with the causes of translator motionII. Vectors and Scalarsa. Scalarsi. Can be described by magnitudeii. E.g., mass, distance, speed, volumeb. Vectorsi. Have both magnitude and directionii. E.g., velocity, force, accelerationiii. Vectors are represented by arrowsIII. Linear vs. Angular Motiona. Linear Motioni. AKA translation or translational motionii. Movement on straight or curved pathwayiii. All points on a body move same distance, same timeb. Angular Motioni. Motion around some pointii. Different regions of the same body segment do not move through the same distanceIV. Position and Displacementa. Positioni. Defines an object’s location in space (relative to some reference)ii. A scalar, not to be confused with displacementb. Distancei. A scalarii. Change in position (without direction)c. Displacementi. Defines the change in positionii. Displacement is a straight line between start and finishiii. Displacement is a vectorV. Important Parametersa. Position WHERE?i. Location in space relative to some reference pointii. Linear and angular positionb. Displacement & Distance HOW FAR?i. Displacement1. Final change in position2. Vector quantityii. Distance1. Sum of all changes in position2. Scalar quantityc. Velocity and Accelerationi. Velocity HOW FAST?1. Vector quantity2. Change in position / timeii. Acceleration HOW QUICKLY IS VELOCITY CHANGING?1. Vector quantity2. Change in velocity / timeVI. What is a Projectile?a. An object that is only acted on byi. Gravityii. Air resistanceb. We have no control over the object once we lose contact with itc. Thrown implements (ball, discus, shot) and airborne humans (long jump, high jump) can be projectilesVII. Two Dimensionsa. The parabolic trajectory of projectilesi. Vertical velocity is zero at peak heightii. Horizontal velocity is unchangediii. Peak height occurs at ½ total horizontal distance, and at ½ total time (when starting and ending at the same height)VIII. Types of Anglesa. Absolute Anglei. An absolute angle is measured from an external frame of referenceb. Relative Anglei. A relative angle is the angle formed between two limb segmentsIX. Angular and Linear Positiona. The linear displacement can be determined when the length of the segment (radius) and the angular displacement are knownX. Angular and Linear Velocitya. The linear velocity can be determined when the length of the segment (Radius) and the angular velocity are knownXI. Centripetal (Radial) Accelerationa. Even at constant angular velocities, the direction of the linear velocity changes when going around a curveb. Since velocity is changing, there must be accelerationc. This acceleration is towards the center of rotationi. Called centripetal acceleration XII. Sources of Forces Affecting Human Movementa. External (environmental)i. Gravityii. Impacts, collisionsiii. Ground/object contact reactions (normal, shear)iv. Fluid (air, water, etc.), pressure, viscosityb. Internal (biological)i. Muscle contractionii. Biomaterial properties (strength, elasticity, inertia)iii. Fluid (air) pressurec. Inertiai. The resistance of any physical object to any change in its state of motion, including changes to its speed and directionXIII. Forcea. Forces alter the motion and/or change the shape of an object b. Forces have both magnitude and directioni. Vectorc. Forces have points of application and lines of actiond. Force has units of NewtonsXIV. Center of Massa. The center of mass is the mean location of all the mass in a system XV. Weighta. Weight is the force produced by the acceleration of gravity on an objectb. Weight does not equal massc. Weight is a vector quantityXVI. Types of Forcesa. Ground Reaction Force (GRF)i. Force exerted by the ground on a body in contact with itb. Joint Reaction Force i. Force experienced at a jointc. Inertial Forcei. Force opposite in direction to an accelerating force acting on a bodyd. Muscle Forcei. Force when muscle fibers generate tensione. Elastic Forcei. The tendency of solid materials to return to their original shape after being deformedf. Friction Forcei. The force acting parallel to the interface of two contacting surfaces duringmotion or impending motionXVII. Torquea. Torque is often referred to as rotary force and is the angular equivalent of linear forceb. Torque is the product of force (F) and the perpendicular distance (d) from the force’s line of action to the axis of rotationi. Vectorc. The units of torque are newton-metersXVIII. Newton’s Laws of Motiona. 1st Law: Law of Inertiai. A body tends to stay at rest or in uniform motion unless acted upon by anunbalanced external forceb. 2nd Law: Law of Accelerationi. Force = mass x accelerationii. Torque = moment of inertia x accelerationc. 3rd Law: Law of Action-Reactioni. For every action, there is an equal and opposite reaction (on different objects)XIX. Free Body Diagramsa. Called a force diagrami. To analyze the forces and moments acting on a bodyXX. Momentuma. Inertia in motion – or mass in motionb. Carries the notion of both mass (inertia) and velocity