1. Physical Science Chapter Four Acceleration Momentum Newton Gravity Free Fall Air Resistance

2. Newton Newton’s Second Law of Motion A net force acting on an object causes the object to accelerate in the direction of the force

3. Acceleration Acceleration is determined by mass of the object and size of the object Force equals mass times acceleration F = ma Units, mass in kilograms, acceleration in meters per second squared Kg. m/s 2 = Newtons = N

4. Falling Objects fall at the same rate no matter what mass they have Gravity causes falling objects to accelerate at 9.8 m/s 2 This pertains to falling objects and not throwing objects

5. Air Resistance Air resistance is the force air exerts on a moving object Air resistance acts in the opposite direction of objects motion This is why a feather doesn’t fall as fast as a penny, but will if there was no air resistance

6. Air Resistance Air resistance depends on an objects shape, density, speed and size

7. Terminal Velocity Terminal velocity is the highest velocity that will be reached by a falling object When air resistance and gravity balance, acceleration stops

8. Projectiles Anything that is thrown or shot through the air Horizontal motion Motion parallel to the Earth’s surface Vertical Motion Motion perpendicular to the Earth’s surface Gravity pulls object downward

9. Centripetal Centripetal acceleration Acceleration toward the center of a curved or circular path Centripetal force Force acting toward the center of a curved or circular path Diagram page 102

10. Free Fall Object moves because of the influence only of gravity

11. Newton Netwon’s Third Law To every action force there is an equal and opposite reaction force Forces can be equal by not balanced Action-Reaction Pairs

12. Momentum Property of a moving object because of its mass and velocity Momentum equals mass times velocity Momentum is signified by a letter p p = mv Mass is in kg and velocity is in meters per second p = kg. m/s

13. Momentum Momentum has a direction like velocity Greater mass equals more momentum Greater velocity equals more momentum Momentum only changes when the objects mass, velocity or both change

14. Law of Conservation of Momentum States that the total amount of momentum of a group of objects does not change unless outside forces act on the object