1. Speed & Following Distance Transportation: Ch. 1, Act. 2

2. What do you think? What is a safe distance between your car and the car in front of you? – Depending on your drivers education program: 2 seconds 3 seconds 1 car length for every 10 mph How do you decide?

3. What is kinematics? Kinematics is the study of motion. – Measurement of speed. – Measurement of acceleration.

4. Speed How do we measure it? – Speed (v) = distance (d) / time (t) v = d/t

5. Average vs. Instantaneous Speed? Average Speed: Total distance traveled / total time. – Average speed is independent of the path traveled. – Average speed does not necessarily reflect your speed at a given moment in time. Instantaneous Speed: The speed that you are traveling at at a specific moment in time. – Speedometer reading.

6. Observing Speed Speed can be observed and represented in a couple of ways. – Motion Diagrams: A strobe representation through pictures of a moving object taken at a specific time interval. – Graphs: Speed can be determined through graphical analysis where the distance or velocity of an object may be measured vs. time.

7. Motion Diagrams Stationary: Fast: Slow: Time

8. Graphical Analysis of Motion Distance vs. time: When the motion is uniform, the slope of the line will give you the speed (v =  d/  t). Time (t 2, d 2 ) (t 1, d 1 ) Slope (m) = (d 2 – d 1 ) (t 2 – t 1 )

9. Describe the Motion Time Constant speed. Time Constant speed followed by not moving.

10. Describe the Motion Time Constant speed in the positive x- direction followed by not moving, followed by moving at constant speed in the negative direction. Constant speed in the positive x- direction followed by a faster speed in the positive x-direction. Time

11. Describe the Motion Uniform accelerated motion. Time

12. Following distance What do you think is a safe following distance? – Experts say that 2 seconds between vehicles is required to keep a safe distance from the vehicle in front of you. How many feet is this at: 25 mph? 55 mph? 75 mph? – Do these results surprise you? 161 feet 73 feet 220 feet