1. ©2008 by W.H. Freeman and Company Displacement There is a distinction between distance and displacement. Displacement (blue line) is how far the object is from its starting point, regardless of how it got there. Distance traveled (dashed line) is measured along the actual path.

2. ©2008 by W.H. Freeman and Company Displacement Left: Displacement is positive. Right: Displacement is negative. The displacement is written:

3. ©2008 by W.H. Freeman and Company Average Velocity Speed: how far an object travels in a given time interval Velocity includes directional information:

4. ©2008 by W.H. Freeman and Company A particle at t1 = -2.0 s is at x1= 3.4 cm and at t2 = 4.5 s is at x2= 8.5 cm. What is its average velocity? Can you calculate its average speed from these data? The average velocity is given by The average speed cannot be calculated. To calculate the average speed, we would need to know the actual distance traveled, and it is not given.

5. ©2008 by W.H. Freeman and Company An airplane travels 3100 km at a speed of 790 km/h and then encounters a tailwind that boosts its speed to 990 km/h for the next 2800 km. What was the total time for the trip? What was the average speed of the plane for this trip? The average speed of the plane for the entire trip is. The average speed for each segment of the trip is given by, so for each segment. For the second segment, Thus the total time is For the first segment,