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Mrs. W's Super Spectacular Science Site |
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Class Notes On this page you will find the daily class notes. They should be especially helpful to you if:1. You are absent and want to stay caught up on what happened in class,
2. You have gaps in your own notes, 3. You need another tool to help you study for a test. Matter in Motion Chapter 5 Section 1: Measuring Motion Observing Motion Reference Point – An object that appears to stay in place Motion – a change in position over time Reference Direction – EX: The cardinal and ordinal directions on a compass rose; left/right; up/down; backward/forward, etc. Common Reference Points 1. non-moving objects (mountains, buildings, trees) 2. moving objects (hot air balloon, birds) 3. Earth's surface (lakes, rivers, oceans, mountain ranges) 4. Earth (moves around the sun, relationship to other planets, stars) Speed Depends on Distance & Time Speed – the rate at which an object moves Depends On: 1. distance 2. time Velocity: Direction Matters Velocity – the speed of an object in a particular direction Don’t confuse speed and velocity.
Acceleration – the rate at which velocity changes To accelerate means to change velocity. The faster the velocity changes, the greater the acceleration is Section 2: Force Force – a push or a pull All forces have: 1. size 2. direction Don’t confuse force and pressure (the amount of force exerted in a given area) Forces in Combination Net force – force that results from combining all the forces exerted on a object Balanced and Unbalanced Forces Unbalanced Force – when the net force on an object is not zero UF produce a change in motion (acceleration) UF are necessary to cause a non-moving object to move UF are necessary to change the motion of a moving object Balanced Force – when the forces applied to an object produce a net force of zero BF produce no change in motion BF don’t cause a non-moving object to start moving Section 3: Friction Friction – a force that opposes motion between two surfaces that are touching Depends on 1. surface area 2. amount of force applied Rougher surfaces create more friction The rougher the surface, the > the friction. The smoother the surface, the < the friction. Greater force causes more friction If the amount of force is >, the amount of friction between the surfaces > The more massive the objects, the > the amount of friction. The less massive the objects, the < the amount of friction. Types of friction: 1. Sliding – effective at opposing movement of objects; force is large 2. Rolling – force is less than that of sliding friction 3. Fluid – less than sliding friction; opposes the motion of objects traveling through a fluid 4. Static – when a force applied to an object does not cause the object to move Friction: Harmful & Helpful Ways to Reduce Friction 1. Lubricants – substances that are applied to surfaces to reduce the friction between them 2. Switch from sliding to rolling friction 3. Make surfaces that rub together smoother Ways to Increase Friction 1. Make surfaces rougher 2. Increase the force pushing the surfaces together Section 4: Gravity Gravity – force of attraction between objects that is due to their masses
L.U.G. – Part 1 A. Gravitational force increases as mass increases L.U.G. – Part 2 B. Gravitational force descreases as distance increases Measures of G.F. Weight – a measure of the gravitational force exerted on an object Mass – the amount of matter in an object |
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