Motion, Speed, & Velocity

1. Motion, Speed, & Velocity

2. What is motion anyway?? • 1. What is meant by saying that motion is relative? For everyday motion, what is motion usually relative to?

3. Motion • Motion is a change in position (relative to a reference point) *reference point- stationary (still) object

4. Conclusion Distance vs. Displacement • Distance is the length of the path traveled. • Displacement (from “dis”-place to “dat”-place) (Brendan Jackson this joke is for you!  I know how much you love them!) is the length and direction of a line from start to finish. • Displacement is a vector quantity that contains both magnitude and direction.

5. Distance vs. Displacement • Distance vs. Displacement -path that is traveled -change in position of an object -can be a straight line -must be a straight line -no particular direction -must always indicate direction is needed

6. Distance and Displacement • 8km = Distance • 3km NE = Displacement

7. What is the coach's resulting displacement and distance of travel?

8. Answer • The coach covers a distance of • (35 yds + 20 yds + 40 yds) = 95 yards and has a displacement of 55 yards, left.

9. Speed • Speed- how fast something moves; must measure 2 quantities 1. distance- traveled by object 2. time- it took to travel that distance • Speed equationS = d t Always remember units! d= meters, kilometers t= sec, min, h s= m/s, m/min, km/h Graphing speed= time on x-axis Distance on y-axis *The slope shows speed

10. Speed • Speed is a measure of how fast something is moving. • It is the rate at which a distance is covered • Units of speed could be: km/h, m/s, mi/h, ft/s • In physics we use units of m/s for speed • s = d/t d s t

11. 3 types of Speed • Instantaneous- rate of motion at any second ex. Speedometer • Constant- speed that does not vary (most speeds are not constant) • Average- total distance traveled divided by the total time (good at describing a bike or car trip)

12. Instantaneous Speed • Instantaneous speed is speed at any instant in time. • A speedometer measures speed in ‘real time’ (the instantaneous speed).

13. Average Speed • Average speed is the average of all instantaneous speeds; found simply by a total distance/total time ratio • Theaverage speed of a trip:

14. 200 160 120 Distance in Feet 80 40 0 1 2 3 4 5 6 7 8 9 Time in Seconds Motion Graphs- Position-Time Graph Distance (ft) Vs. Time (sec.) Rise Run The Slope is Equivalent to the Average Speed

15. Motion Graphs – Position vs. Time constant, rightward (+) velocityof +10 m/s a rightward (+), changing velocity- that is, a car that is moving rightward but speeding up or accelerating

17. Velocity • Velocity- describes both speed & direction (east, west, north, south, up, or down) of an object • Velocity can change even when the speed is constant, simply by changing directions • V = d t

18. Velocity Triangle • Speed and velocity triangles are similar because v = d/t • Find the equation for displacement, and time using the triangle • d = v x t • t = d/v d v t

19. Velocity and Speed • In physics we distinguish between speed and velocity: • Speed refers to how quickly an object moves (a scalar quantity). • Velocity is defined as speed in a given direction or rate of change of position (displacement over time). v = x/t • Velocityrefers to both the speed and direction of motion of an object (a vector quantity). • Motion atconstant velocity means that both the speed and direction of an object do not change. • In a car, we can change the velocity three ways: gas pedal to speed up, brake to slow down or steering wheel to change direction

20. What 2 controls on a car enable a change in speed?

22. Name another control that enables a change in velocity.