1. Unit 3: Motion, Forces, & Energy Chapter 9: Motion & Energy
Big Idea: You can describe the motion of an object by its position, speed, direction, & acceleration

2. 4 Sections Describing Motion Speed & Velocity Acceleration Energy
Mrs. Lee - Ch 9

3. Sec 1: Describing Motion
KEY CONCEPTS
An object is in motion if it changes position relative to a reference point
Distance is the total length of the actual path between 2 points. Displacement is the length & direction of a straight line between starting & ending points
Mrs. Lee - Ch 9

4. Sec 1: Key Terms Motion Reference point Distance Displacement Vector
Mrs. Lee - Ch 9

5. Sec 2: Speed & Velocity KEY CONCEPTS
To calculate the speed of the object, divide the distance the object travels by the time it takes to travel that distance
Speed = Distance
Time
Changes in velocity may be due to changes in speed, changes in direction, or both
Mrs. Lee - Ch 9

6. Sec 2: Speed & Velocity (cont’d)
The slope of a distance vs. time graph represents speed -- the rate that distance changes in relation to time
Slope = Rise
Run
Mrs. Lee - Ch 9

7. Sec 2: Key Terms Speed Average speed Instantaneous speed Velocity
Slope
Mrs. Lee - Ch 9

8. Sec 3: Acceleration KEY CONCEPTS In science, acceleration refers to:
1) increasing speed
2) decreasing speed
or 3) changing direction
To determine the acceleration of an object, you must calculate its change in velocity per unit of time
Mrs. Lee - Ch 9

9. Sec 3: Acceleration (cont’d)
Acceleration = Final velocity – Initial Velocity
Time
You can use both a speed vs. time graph & a distance vs. time graph to analyze the motion of an accelerating object
Mrs. Lee - Ch 9

10. Sec 3: Key Terms
Acceleration
Mrs. Lee - Ch 9

11. Sec 4: Energy KEY CONCEPTS
The kinetic energy of an object depends on both its mass & its speed
Kinetic Energy = 1 x Mass x Speed2 2
An object’s gravitational potential energy depends on its weight & on its height relative to a reference point
Mrs. Lee - Ch 9

12. Sec 4: Energy (cont’d) Gravitational potential energy =
Weight x Height
Mechanical energy =
Potential energy + Kinetic energy
Mrs. Lee - Ch 9

13. Sec 4: Energy (cont’d)
Any object that rises or falls experiences a change in its kinetic & gravitational potential energy
According to the law of conservation of energy, energy cannot be created or destroyed
Mrs. Lee - Ch 9

14. Sec 4: Key Terms Work Energy Kinetic energy Potential energy
Gravitational potential energy
Elastic potential energy
Mechanical energy
Law of conservation of energy
Mrs. Lee - Ch 9