WA.4. Physical Science
PS1. Force and Motion
6-8.PS1. Balanced and Unbalanced Forces: In prior grades students learned to use basic tools to measure force, time, and distance. In grades 6-8 students learn to measure, record, and calculate the average speed of objects and to tabulate and graph the results. They also develop a qualitative understanding of inertia. Students learn to predict the motion of objects subject to opposing forces along the line of travel. If the forces are balanced, the object will continue moving with the same speed and direction, but if the forces are not balanced, the object's motion will change. These concepts and principles prepare students for a more formal understanding of mechanics in high school and help them make sense of the world around them.
6-8.PS1A. Students know that average speed is defined as the distance traveled in a given period of time.
6-8.PS1A.1. Students are expected to measure the distance an object travels in a given interval of time and calculate the object's average speed, using S = d/t. (e.g., a battery-powered toy car travels 20 meters in 5 seconds, so its average speed is 4 meters per second).
6-8.PS1A.2. Students are expected to illustrate the motion of an object using a graph, or infer the motion of an object from a graph of the object's position vs. time or speed vs. time.