KIN 3309 1nd Edition Lecture 16 Outline of Last Lecture I. OutlineII. Kinematics vs. KineticsIII. Sources of Forces Affecting Human MovementIV. ForceV. Composition and Resolution of ForcesVI. Newton’s Laws of MotionVII. Newton’s 1st Law: Law of InertiaVIII. Newton’s 2nd Law: Law of AccelerationIX. Newton’s 3rd Law: Law of Action-ReactionX. MomentumXI. Center of MassXII. Gravity (Noncontact Force)XIII. WeightXIV. Contact ForcesXV. Ground Reaction Force (GRF)XVI. Center of Pressure (COP)XVII. Linear Kinetics of LocomotionXVIII. Joint Reaction Force (JRF)These 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.XIX. Inertial ForceXX. Muscle ForceXXI. Elastic ForceXXII. QuizOutline of Current Lecture I. Newton’s Laws of MotionII. Momentum, Weight, COMIII. Contact ForcesIV. OutlineV. Free Body DiagramsVI. Effects of a Force at an Instant in TimeVII. FrictionVIII. Impulse: Force Applied over a Period of TimeIX. Work: Force Applied over a DistanceX. PowerXI. EnergyXII. Work-Energy TheoremXIII. Conservation of EnergyXIV. Energy Conversion during GaitXV. QuizCurrent LectureI. 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 accelerationc. 3rd Law: Law of Action-Reactioni. For every action, there is an equal and opposite reaction (on different objects)II. Momentum, Weight, COMa. Momentumi. Inertia in motion – or – mass in motionii. The quantity of motion of an objectb. Weighti. Weight is the force produced by the acceleration of gravity on an object (weight does not equal mass)c. Center of Mass (COM)i. The mean location of all the mass in a systemIII. Contact 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 deformedIV. Outlinea. Free body diagram (a.k.a., force diagram)b. Effects of a force at an instant in timec. Types of contact forces in human movementi. Frictiond. Impulsee. Work f. Powerg. Energyh. Work-Energy Theoremi. Conservation of EnergyV. Free Body Diagramsa. Called a force diagrami. To analyze the forces (linear) and moments (angular) acting on a bodyii. Display magnitude and direction of forcesVI. Effects of a Force at an Instant in Timea. If acceleration is zero, biomechanical study of the human is referred to as a static analysisb. If acceleration is not zero (and is significant), biomechanical study of the human is referred to as a dynamic analysisc. Static Analysisi. Systems at rest or constant velocityd. Dynamic Analysisi. Systems in motion (accelerating or decelerating)VII. Frictiona. Friction is the force acting parallel to the interface of two contacting surfaces during motion or impending motioni. The “normal force” is importantb. The “normal force” is the force acting perpendicular (“normal”) to the surfacei. Newton’s 3rd Law (La w of Action-Reaction)ii. Often simply the weight of the object, in the + directionc. The coefficient of friction is greater when an object is not movingd. Friction for a given object is not affected by the surface area in contactVIII. Impulse: Force Applied over a Period of Timea. An object with momentum can be stopped if a force is applied against it for a given amount of timeb. Force applied over a period of time: impulse = change in momentum!c. Impulse is vector quantity, the direction is the same as the direction of the forced. Symbolized as Ie. Units = kgm/s or NsIX. Work: Force Applied over a Distancea. Work = Force x Distanceb. The scientific definition of work is: using a force to move an object a distance (when both the force and the motion of the object are in the same direction)c. Units of work are Joules (1 J = 1 Nxm)d. Work is a scalar quantitye. Work is not a function of timeX. Powera. Power is the rate at which work is doneb. Power = work/time c. Also, power = force x velocityd. Units of power are Watts (W = J/s)e. Power is a scalar quantityXI. Energya. Energy is the capacity of a physical system to perform workb. Kinetic Energy (KE) results from motionc. Potential Energy (PE) results from position in gravitational fieldd. Units of energy are Joules (J)e. Energy is a scalar quantityf. Strain (elastic) energy (SE) is the capacity to do work due to deformation of a bodyXII. Work-Energy Theorema. The work done by a resultant force is equal to the change in energy that it producesb. This is assuming that no work is done to deform the system (i.e., no strain energyis stored)c. This also assumes that no work is done to increase rotational kinetic energyXIII. Conservation of Energya. The total energy of a closed system is constant since energy does not enter or leave a closed systemb. This only occurs in human movement when the object is a projectile and we neglect air resistancei. TE = PE + KEc. Note that gravity does not change the total energy of the systemXIV. Energy Conversion during Gaita. Walking and running are characterized by energy conversionsi. Walking1. Kinetic-potential energy conversionii. Running1. Kinetic and potential energy are converted to elastic, and vice-versaXV. Quiza. If the static coefficient of friction of a basketball show on a particular playing surface is 0.58 and the normal force is 911 N, what horizontal force is necessary to cause the shoe to slide?i. 528.38Nb. The limiting fiction between the 25 kg bag and the cart is 50 N. You need to slide the bag to the side of the cart. If you apply 50 N horizontally on the bag…i. The bag will remain motionlessii. The bag will begin to slideiii. The bag will rise off the cartiv. Need more info to calculatev. (Friction force is 50 N, you are applying the same exact amount of force)Quiz 2:- Chapter 8-10 is 98% of the quiz- Definitions:o Kinetics, kinematics, angular velocity, relative angle, joint angles, and that impulse is change in momentum etc.- Example 5: Dynamic Analysis Questions will be on the