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.PS1B. Students know that friction is a force that can help objects start moving, stop moving, slow down or can change the direction of the object's motion.
6-8.PS1B.1. Students are expected to demonstrate and explain the frictional force acting on an object with the use of a physical model.
6-8.PS1C. Students know that unbalanced forces will cause changes in the speed or direction of an object's motion. The motion of an object will stay the same when forces are balanced.
6-8.PS1C.1. Students are expected to determine whether forces on an object are balanced or unbalanced and justify with observational evidence.
6-8.PS1D. Students know that the same unbalanced force will change the motion of an object with more mass more slowly than an object with less mass.
6-8.PS1D.1. Students are expected, to given two different masses that receive the same unbalanced force, predict which will move more quickly.