Kinematics

1. Kinematics The study of how objects move

2. Where are You? We must start with a question

3. Position To find where you are you need the following: Reference Point: Zero location in a coordinate system or frame. Position:Separation between an object and a reference point. It needs a distance and direction. i.e. 3.0 meters to the right. Frame of Reference: Coordinate system used to define motion.

4. You are Here

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12. Distance vs. Displacement 50 m Distance is simply the total path length traversed in moving from one location to another Distance is a SCALAR quantity. A measurement with only magnitude, or size.

13. Distance vs. Displacement 10 m East Displacement is the straight-line distance between two points, along with the direction from the starting point to the final position. Displacement is a VECTOR quantity. A measurement with magnitude, or size and a direction

14. Walking to Physics Lab Difference between Distance and Displacement Distance = 8 m Displacement = 8m right Displacement =+8m Direction Convention : Right - Positive Left - Negative

15. Speed Speed is the rate at which distance is traveled. 20 m 2 sec Speed is a scalar quanity =10 m/s

16. Average vs. Instantaneous Speed Average speed is the distance d traveled, the actual path, divided by the total time t elapsed in traveling that distance. Instantaneous Speed is how fast an object is moving at a particular instant of time.

17. Velocity Velocity tells how fast something is moving and in what direction. Velocity is a vector quantity. Average Velocity is the displacement divided by the total travel time =initial position, commonly zero = initial time, commonly zero When xo and to are zero

18. Speed and Velocity Problem • A jogger jogs from one end to the other of a straight 300 meter track (from point A to point B) in 2.50 min and then turns around and jogs 100 m back toward the starting point (to point C) in another 1.00 min. What are the jogger’s average speeds and velocities in going • From A to B • B) From A to C after turning around

19. Given: xB = 300m - 0m = +300m (from A to B) xC = 200m – 300m = -100m (from B to C) tB = 2.50 min = 150 s tC = 1.00 min = 60.0 s A) Average speed and velocity from A to B B) Average speed and velocity from A to C

20. Two Components of Velocity

21. Graphical look at Motion

28. Acceleration Position is the separation between an object and a reference point. Displacement is a change in position Velocity is the time rate change of displacement Acceleration is the time rate change of velocity All four are vector quantities Represented by a magnitude and direction

29. Kinematic Equations

30. velocity acceleration

31. Total Displacement and total time With a constant acceleration Average Velocity

34. Kinematic Equations

35. Problem: Ally the Alligator takes off from an airfield. She starts from rest and obtains a velocity of 36 m/s at take off in 20.0 seconds. What is her acceleration down the runway? How far did she go down the runway?