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Focus on Physical Science
Motion
- The velocity of an object is the rate of change of its position. As a basis for understanding this concept:
- Students know position is defined in relation to some choice of a standard reference point and a set of
reference directions.
- Students know that average speed is the total distance traveled divided by the total time elapsed and that
the speed of an object along the path traveled can vary.
- Students know how to solve problems involving distance, time, and average speed.
- Students know the velocity of an object must be described by specifying both the direction and the speed of
the object.
- Students know changes in velocity may be due to changes in speed, direction, or both.
- Students know how to interpret graphs of position versus time and graphs of speed versus time for motion in
a single direction.
Forces
- Unbalanced forces cause changes in velocity. As a basis for understanding this concept:
- Students know a force has both direction and magnitude.
- Students know when an object is subject to two or more forces at once, the result is the cumulative effect
of all the forces.
- Students know when the forces on an object are balanced, the motion of the object does not change.
- Students know how to identify separately the two or more forces that are acting on a single static object, including gravity, elastic forces due to tension or compression in matter, and friction.
- Students know that when the forces on an object are unbalanced, the object will change its velocity (that is, it will speed up, slow down, or change direction).
- Students know the greater the mass of an object, the more force is needed to achieve the same rate of change in motion.
- Students know the role of gravity in forming and maintaining the shapes of planets, stars, and the solar system.
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