1. Principles of Physics

2.  motion along a straight line path, motion in one dimension  Which way are you headed?  How far did you go?  How fast are you going?  Is your speed changing?

3. Velocity  Rate at which position changes  In other words, how quickly the position of an object changes during the time interval  Measured in meters per second (miles per hour in the USA)

4.  Velocity is calculated = average velocity (m/s) d = displacement (m) t = time (s)  Average because we don’t know exactly what is happening from the 1 st position to the next ▪ The object could be speeding up and slowing down along the way  Vector quantity – has direction  Direction is + when right, up, north, or east  Direction is – when left, down, south, or west

5.  Instantaneous speed = speed at any particular point  Can be determined by speedometer, but not by

6. 1. Rick walked 50 m in 60 s. What was his average speed? Givens: d = 50 m t = 60 s v = ?

7. 2. A car has an average velocity of 20 m/s east. How long would it take the car to travel 85 m? Givens: v = 20 m/s t = ? d = 85 m

8. 3. Anna watches a thunderstorm from her window. She sees the flash of a lightning bolt and begins counting the seconds until she hears the clap of thunder 10.0 seconds later. Assuming that the speed of sound in air is 330 m/s, how far away was the lightning bolt? (Assume that she sees the bolt instantaneously). Givens: v = 330 m/s t = 10 s d = ?