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Ch. 10 Motion. I. Measuring Motion. A. Observing Motion 1. Frame of reference is used to observe motion a. Using a stationary object to compare movement 2. Direction is needed to determine motion (N, S, E, W) 3. Distance is needed to determine motion.
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I. Measuring Motion A. Observing Motion 1. Frame of reference is used to observe motion a. Using a stationary object to compare movement 2. Direction is needed to determine motion (N, S, E, W) 3. Distance is needed to determine motion
Relative motion (river) http://physci.kennesaw.edu/javamirror/ntnujava/relativeVelocity/relativeVelocity.html Relative motion (ball drop) http://www.phys.unsw.edu.au/einsteinlight/jw/module1_Galileo_and_Newton.htm Plane crash on the Hudson http://www.msnbc.msn.com/id/28688358/displaymode/1176/rstry/28688215/ Average speed demo http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/kinema/trip.html
A DISTANCE B C TIME Speed = Distance/Time (M / S) (MILES / HOUR) 1. Speed can be graphed a. Time = X-axis Distance = Y-axis b. Speed can be determined by the slope of the line 1. Line A Stops 2. Line B Constant Speed 3. Line C Accelerates 2. Average Speed = Total Distance / Total Time 3. Instantaneous Speed = Speed at a given point 4. Velocity = Speed in a given direction a. Combine velocity (ADD) to calculate resultant velocity -walking on a moving bus (BOOK)
II. Acceleration= Change in velocity A. Change in speed 1. Speeding up 2. Slowing down B. Change in direction 1. Turning a forward moving car to the left of the right 2. Circular motion = Constant acceleration (CONST. CHNG OF DIRECTION)
Calculating Acceleration = VF - VI T F= Final I = Initial T = Time • Acceleration can be determined from a velocity/time graph A = Zero Acceleration B = Constant acceleration C = Positive accel. – Negative accel. Positive – Negative A VELOCITY B C TIME
III. Motion and Force A. Balanced and unbalanced forces 1. Balanced force = No change in motion 2. Must have an unbalanced force to change motion B. Force of friction (opposes motion) 1. Static friction = Attraction of molecules of stationary object – Opposes initial movement
2. Kinetic Friction A. sliding friction = a book sliding on a desk B. rolling friction = a car on a road C. Fluid friction = a car on ice
C. Harmful friction can be reduced 1. Lubricants reduce friction a. Oil on engine parts b. Grease in bearings 2. Zamboni on hockey ice 3. Shape of a bicycle helmet 4. Cyclist clothes - Spandex are tight to fit to reduce drag
D. Helpful friction can be increased 1. Sand on icy roads 2. Cleated shoes – baseball/football 3. Pine-tar = Baseball bats