1. What we did in class today: Tuesday January 10 th, 2012 Note cards Newton’s Laws Experiment If absent make-up note cards

2. Force is a push or a pull. Example: Forces are used to pick up a backpack, close a car door, or move a pencil across the desk top.

3. Mass is a measure of how much matter an object contains. Example: A basketball has more mass than a baseball.

4. Work is done on an object when the object moves in the same direction in which the force is exerted.

5. Power is the rate at which you do work. Example: A cook increases his power when he beats eggs rapidly instead of stirring slowly. To calculate power, divide the amount of work by the time it takes to do the work.

6. Speed Speed is how fast something moves or the distance it moves in a given amount of time. To calculate speed you need to know both distance and time measurements. s = d/t (m/s)

7. Average speed is calculated by dividing total distance by total time. Example : A middle school runner has the following times for the four laps of a 1600-meter race: 83 seconds, 81 seconds, 79 seconds, and 77 seconds. The total time is 320 seconds and the total distance is 1600 meters. The average speed is 1600 meters divided by 320 seconds or 5 meters per second.

8. Instantaneous speed is the speed at which you are currently traveling at the moment. Example: If you are driving along and look down at the speedometer, your instantaneous speed would be displayed on your speedometer.

9. Velocity is a speed in a specific direction. Example: If you say you are walking east at the speed of three meters per second, you are describing velocity.

10. Acceleration Acceleration is a measure of how quickly the velocity is changing. If velocity does not change, there is no acceleration. ( m/s 2 ) a = v final – v initial t

11. Positive acceleration occurs when the acceleration is in the same direction as the object is moving and the speed of the object increases. Example: The car speeds up.

12. Negative acceleration occurs when the acceleration is opposite to the motion and the speed of the object decreases. Example: The car slows down.

13. Newton’s Laws of Motion Newton’s First Law states objects at rest remain at rest, and objects in motion remain in motion with same velocity, unless acted upon by an unbalanced force. INERTIA

14. Newton’s Second Law states the acceleration of an object depends on the mass of the object and the amount of force applied. The acceleration of an object increases with increased force and decreases with increased mass. F= mass x acceleration A= force/mass

15. Newton’s Third Law states when one object exerts a force on another object, the second object exerts an equal and opposite force on the first object. Action  Reaction