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Chapter 5 terms AE
Question | Answer |
---|---|
Motion | When an object changes position over time when compared with a reference point |
Speed | The rate at which an object moves |
Average Speed Formula | total distance/total time |
Velocity | The speed of an object in a particular direction |
What can cause velocity to change ? (2 things) | Speed Direction |
Acceleration | the rate at which velocity changes |
Acceleration is how fast what changes ? | Velocity |
Acceleration Formula –final velocity | starting velocity/time it takes to change velocity |
Positive Acceleration & Examples | When velocity increases, a plane taking off |
Negative Acceleration & Examples | When velocity decreases, a car stopping at a stop sign |
Centripetal Acceleration & Example | Circular motion, a windmill |
Force | push or pull |
Newton (N) | unit used to express force |
Net Force | the force that results from combining all the forces exerted on an object |
Why are unbalanced forces necessary to cause movement ? | They cause a change in motion |
Balanced Forces | The net force is a zero so there is no movement |
Friction | a force that opposes motion between two surfaces that are touching |
Sources of Friction | Roughness of surfaces and force pushing surfaces together |
Relationship between greater force & friction | Rougher surfaces and greater force make more friction |
Sliding Friction | The force that causes objects to stop moving |
Rolling Friction | Less friction that sliding friction because there is less friction between the wheels and the floor |
Fluid Friction | The fluid is now between your feet and the floor so there is less friction |
Ways to reduce friction lubricants | lubricants are applied to substances to reduce friction between them |
Ways to reduce friction sandpaper | Rubbing sandpaper on an object makes to smoother |
Ways to increase friction | Putting sand on an icy road, textured batting gloves |
Gravity | the force if attraction between objects that is due to their masses. |
Why must force be used to lift objects? | Gravity pulls down on objects |
What does the Law of Universal Gravitation state? (3 parts) | All objects in the universe attract each other through gravitational force. The size of the force depends of the mass of the objects and the distance between them. |