Measuring Motion Chapter 12, Section 1 Part 1

Observing Motion To observe motion, you must observe an object in relation to a reference point. If an object changes position when compared to the reference point, then motion has occurred.

The Earth’s surface and large stationary objects (trees, buildings) can often be used as reference points.

Let’s Try It Describe Miss Muragishi’s position in the classroom using the projector as a reference point. Close your eyes. Now open. Did Miss Muragishi move? How do you know? Answer this question by comparing her new position to the reference point.

Two-Dimensional Motion Motion can be shown on a 4 - quadrant grid. It can be defined as positive or negative. We use ordered pairs to define this motion.

Speed The rate at which an object moves is its speed (m/s).

Speed depends on the distance traveled and the time taken to travel that distance. Average speed = total distance total time

Graphing Speed A distance - time graph shows the motion of an object over a period of time. X- axis = time Y-axis = distance

Example What is the average speed represented by the red line? Av. Speed = distance time Av. Speed = 2400 m 30 min Av. Speed = 80 m/min