1. Forces and Motion Vocabulary

2. Mass – amount of matter in an object

3. Weight- the amount that gravity is pulling down on any mass

4. force- a push or a pull

5. balanced forces- when the effects of the forces acting on an object cancel each other, no change in motion, net force is zero

6. unbalanced forces- when the effects of the forces do not cancel each other, there will be a net force, causes motion

7. net force- the combination of all the forces acting on an object; added if in same direction, subtracted if in opposite directions

8. Reference point: is the starting point you choose to describe the location, or position of an object.

9. Position: is an objects distance in a certain direction from a reference point. Must include the objects distance, direction, and reference point.

10. Distance- (D), the total length traveled, measured in meters (m)

11. Displacement – the total distance and the direction between the starting and ending points in which you travel.

12. Speed – (S), equals the distance (d) traveled divided by the time (t) it takes to travel that distance Formula: s=d/t, Measured in units of meters per second (m/s).

13. Average speed – equals the total distance traveled divided by the total time taken to travel the distance.

14. Instantaneous speed – the speed of an object at one instant of time

15. Inertia – tendency of an object to resist change in its motion.

16. Velocity – (V), speed and direction of a moving object, measured in m/s, with a direction (East, or left etc.)

17. Acceleration – equals the change in velocity divided by the time or the change to take place; occurs when an object speeds up, slows down, or turns. Formula a= sf-si/t; Units are m/s2.

18. Positive acceleration- occurs when an object is speeding up, represented by an upward slope on a speed v. time graph

19. Negative acceleration- deceleration, occurs when an object is slowing down, represented by a downward slope on a speed vs. time graph

20. Friction- the force that brings nearly everything to a stop; can be rolling, static, or sliding.

21. Newton 1st law of Motion- If the net force acting on an object is zero, objects at rest will stay at rest and objects in motion will stay in motion, in a straight line at a constant speed. Also known as the law of inertia.

22. Newton’s second law of motion- The second law states that the greater the mass of an object, the more force it will take to accelerate the object. There is even an equation that says Force = mass x acceleration or F=ma.

23. Third Law of Motion-for every action, there is an equal and opposite reaction.

24. gravity- a force that exists between any two objects that have mass
gravity- a force that exists between any two objects that have mass. Always pulls objects toward each other

25. free fall- a falling object is in free fall when the only force acting on the object is gravity

26. weightlessness- the condition that occurs in free fall when the weight of an object seems to be zero

27. air resistance- form of friction that acts to slow down any object moving in the air

28. terminal velocity- when air resistance balances the force of gravity, the object falls at a constant speed

29. center of mass- the point in an object that moves as if all the object’s mass were concentrated at that point

30. centripetal force- the force that keeps an object moving in a circle, always points toward the center of the circle.