KIN 365 1st Edition Exam #4 Study GuideI. Fluid Forces A. pg 115-116 manual, ch 9 hardback B. Drag Forces 1. parallel component of dynamic fluid force acting in opposite direction ofsystem in motion with respect to fluid 2. tends to resist motion of system C. Lift Forces 1. perpendicular component of dynamic fluid force acting in anydirection perpendicular to system in motion with respect to fluid 2. changes direction of system in motion D. relative motion 1. relative motion between object and fluid force a) ex: headwind, tailwind, side wind 2. important factor is how fast object is going in relation to fluid force (not inrelation to ground) E. Drag force 1. deceleration of motion 2. parallel component of dynamic fluid force 3. acts in opposite direction of system motion with respect to fluid 4. tends to resist the motion of the system through fluid F. Fluid drag force 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.1. aka fluid resistance 2. force in opposite direction of motion of object a) aerodynamic (air) b) hydrodynamic (water) 3. want to go through air/water but something impeding ability of the acceleration ofobject G. Two Types of Drag Force 1. skin friction a) aka surface drag b) boundary layer (1) region of relative motion between adjacent layers of fluid particles c) layer-rubbing friction (1) H2O vs air (2) more friction in water because water is heavier than air d) affected by three factors (1) velocity of flow (a) relative to air (b) faster you move = more friction (2) amount of SA oriented parallel to flow (a) where all rubbing occurs (b) greater area = more friction (3) roughness of surface (a) coefficient of friction (b) more roughness = more friction2. profile drag a) aka pressure or form drag b) main type of drag force acting on us and projections (anything we throw) c) turbulent flow (1) motion around object is turbulent, not smooth (2) other friction forces (besides friction) present (3) goal is to minimize turbulence: streamlining d) laminar and turbulent flow (1) laminar flow (a) smooth (b) no turbulence (c) only friction drag present (2) turbulent flow (a) not smooth (b) very turbulent (c) ex: what we feel when passing an 18 wheeler i) profile drag present in addition to friction drag II. Four Factors That Affect Drag A.Coefficient of Drag (Cd) 1. how streamline object is 2. higher Cd = more drag force = slows 3. examples a) parachute - slows you down b) fish - swims fast through waterc) old cars vs new cars d) leisure vs Olympic bike helmet B. Area (A) 1. frontal area 2. area facing flow 3. larger area = more drag force C. Fluid Density (p) 1. everything to do with altitude 2. more dense fluid = more drag a) more drag at sea level b) less drag at higher altitudes c) more home runs in Denver D. Flow Velocity (v) 1. most important factor 2. little change in relative motion of object to fluid = big difference in drag 3. faster you go = more drag 4. relative motion between object and fluid a) how fast fluid is going with respect to object b) how fast object is going with respect to fluid E. Drag Force = 1/2 * Cd * A * p * v^2 III.Lift Force A. upward/downward motion B. perpendicular component of dynamic fluid force C. can act in any direction that is perpendicular to system motion with respect to fluidD. tends to change the direction of systems motion through fluid IV. Factors Affecting LiftA. Area (A) 1. angle of attack 2. orientation of object that is angled perpendicular to fluid flow 3. ex a) smaller angle = glider b) larger angles = large plane leaves c) large angle = more lift force to point V. Lift Drag ratio A. ratio that expresses the relationship of the amount of lift to amount of drag atangle of attack B. ratio favoring drag will reach stall angle C. Stall angle 1. flight no longer possible VI. Linear Movement and AccelerationA. Newton’s First Law 1. body at rest stays at rest 2. body in motion stays in motion unless acted on by outside force 3. change in motion is caused by an outside force B. Newton’s Second Law 1. acceleration of a system directly proportions to sum of forces (net force)acting upon it and inversely proportional to mass 2. acceleration = sum force/mass 3. degree an object (at some mass) will be accelerated isa) directly proportional to amount of force b) inversely proportional to objects mass C. observed change in state of motion is accelerationVII. AccelerationA. change in magnitude and/or direction of velocity vector with respect to timemeasured in Newtons (N) B. one Newton = force needed for object of one kilogram to be accelerated by onemile per second C. Velocity 1. vector rate of motion 2. has both magnitude and direction 3. rate of motion in specific direction calculated with the following equation a) v=d/(tf-ti) b) velocity = displacement divided by change in time D. Linear Displacement/Distance 1. change in position of object 2. position final - position initial 3. in a straight line 4. measured in linear units (miles, kilometers) 5. d = position final - position initial E. object or system may not have same rate of motion throughout movement 1. rate of motion may not be necessarily a constant through motion 2. can calculate a) average velocity = peak velocity / rate of motion b) instantaneous velocity or rate of motionF. variable velocity 1. average velocity = total distance / time 2. instantaneous or peakvelocity VIII. Linear Momentum A. another factor that affects outcome of interactions between two bodies is momentum B. momentum 1. mechanical quantity that is particularly important in situations involving collisions 2. quantity of motion 3. mass * velocity 4. kg * m/s 5. vector quantity C. if something is moving fast or is big 1. has a lot of momentum 2. takes larger or prolonged force to bring it to a stop D. an object at rest = zero momentum 1. no change in object’s momentum will occur without application of externallyapplied force causing change in velocity of object E. force. momentum relationship 1. F = (mv2 - mv1) / time IX. Aerodynamic LiftA. lift will always be perpendicular to relative flow direction B. lift does not always have to be upward C. ex: ceiling fan 1. leading edges tilted up = air down 2. leading edges tilted down = airup X. Force of Lift A. lift force = 1/2 * Cl * A * p * v^2 B. most important factor is flow