Motion and Stability

1. A force that resists motion when two objects or surfaces come into contact with one another.
4. A factor or condition that can change in an experiment. There are three types of variables: independent, dependent, and controlled.
7. An informed idea about what will happen in the future.
8. An object suspended from a fixed point so it can swing freely back and forth.
11. Force A force equal to the sum of all forces acting on an object.
13. Time needed for a pendulum to make one complete swing back and forth.
14. The amount of matter in an object or substance.
16. The variable in an experiment that the scientist observes and measures. For example, you can measure the growth of a sunny plant vs the growth of a plant kept in a dark closet to see if sunlight causes a difference in plant growth.

2. Any variables that are kept the same throughout an experiment. Every good experiment needs to control certain variables so that the experiment is focused on testing only one thing. For example, the plant on the window and the plant in the closet need to get the same amount of water so the scientists know it was the difference in sunlight and not water that made the plants grow differently.
3. A group of related things that work together as a whole.
5. A series of events that are regularly repeated in the same order.
6. Equal forces that act against each other and do not cause a change in an object's motion.
9. Forces that are unequal in size or direction and cause a change in an object's motion.
10. The variable in an experiment that the scientist changes. For example, in an experiment that tests the effect of sunlight on plant growth, you can change how much light a plant receives by putting one plant near a window and an identical plant in a dark closet.
12. ityA force that pulls objects towards each other.
15. The rate of motion of an object. Measured by how much distance the object traveled within a certain amount of time.