Chapter 4 Notes

# Chapter 4 Notes - ISP 205 Chapter 4 Page 1 4.1 Describing...

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ISP 205 - Chapter 4 Page 1 4.1 Describing Motion: Examples from Daily Life I. How do we describe Motion A. Speed, Velocity, and Acceleration 1. Speed – how far something will go in a certain amount of time 2. Velocity – tells both its speed and direction a. Negative acceleration causes velocity to decrease b. Turning changes velocity because you are changing direction c. Don’t feel effects of constant velocity 3. Acceleration – if velocity is changing in any way, whether in speed, direction or both a. Applies to not only increasing speed but slowing down and turning as well b. Slowing occurs when acceleration is in a direction opposite of motion (negative acceleration) c. Turning is a form of acceleration even if speed is constant B. The Acceleration of Gravity – acceleration of a falling object ( g) 1. Objects accelerate as they fall; accelerate regardless of mass 2. Air resistance causes the difference in acceleration (feather vs rock) 3. On moon – feather and rock would fall at same rate (no air) 4. Objects fall faster by 9.8 m/s (10 m/s). a. 1 second = 10 m/s; 2 seconds = 20 m/s b. 10 meters per second per second (g = 9.8 m/s 2 ) C. Momentum and Force 1. Momentum – combination of mass and velocity (mass x velocity) 2. Only way to change an object’s momentum is to apply a force to it 3. Greater mass = more momentum (even at same velocity) 4. Collisions transfer momentum; the sudden change in momentum becomes force 5. Net Force (overall force) – acting on an object represents the combined effect of all the individual forces put together – is none at constant velocity 6. A change in momentum occurs only when the net force is not zero 7. An object must accelerate whenever a net force acts on it 8. Planets are always accelerating as they orbit the Sun because their direction of travel constantly changes as they orbit II. Mass vs. Weight A. Mass – amount of matter in your body: SAME no matter where B. Weight – force that is acting on your mass: CAN VARY C. Free-Fall and Weightlessness 1. Free-fall – falling without any resistance to slow you down 2. When you free-fall you are weightless D. Weightlessness in Space 1. People or objects are weightless whenever they are falling freely and astronauts in orbit are weightless because they are in a constant state of free-fall 2. All orbiting objects stay in orbit because they are constantly “falling around” the Earth

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ISP 205 - Chapter 4 Page 2 4.2 Newton’s Laws of Motion I. How Newton Changed our View of the Universe A. 1666 – saw an apple fall to the ground and realized that the gravity making the apple
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## This note was uploaded on 03/19/2008 for the course ISP 205 taught by Professor Donahue during the Spring '08 term at Michigan State University.

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Chapter 4 Notes - ISP 205 Chapter 4 Page 1 4.1 Describing...

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