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# Newtons laws

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• ### Newtons laws

1. 1. Newton’s Laws of Motion Red - Write it Teks: 8.6a- Demonstrate and calculate how unbalanced forces change the speed or direction of an object in motion 8.6b- differentiate between speed, velocity and acceleration Blue - Highlight it
2. 2. 1. Motion: A change in Position <ul><li>A. Distance vs. Displacement </li></ul><ul><li>1. Distance: the entire path of travel OR how far you went. </li></ul>2. Displacement: the straight line measurement (distance) between starting & ending points (including direction).
3. 3. 2. Speed vs. Velocity <ul><li>Speed: distance traveled divided by the time needed to travel. </li></ul><ul><li>Velocity: displacement (although distance is usually used) divided by time including direction of travel. </li></ul><ul><li>Formula: s = d/t </li></ul><ul><li>Mathematically, Speed and Velocity are the SAME; Velocity adds a direction </li></ul>
4. 4. 3.Graphing Speed: distance over time <ul><li>Constant Speed (top) </li></ul><ul><ul><li>As the time changes, the distance changes. </li></ul></ul><ul><ul><li>The steeper the slope, the faster the speed (more distance in less time). </li></ul></ul><ul><ul><li>The shallower the slope, the slower the speed (more time to cover less distance). </li></ul></ul><ul><li>Object at rest (bottom) </li></ul><ul><ul><li>As the time changes, the distance remains unchanged. </li></ul></ul>
5. 5. 4. Acceleration <ul><li>Acceleration: change in velocity divided by the time needed for the change. </li></ul><ul><li>Since acceleration is a change in velocity , </li></ul><ul><li>If you change direction, even without changing speed, you are accelerating! </li></ul><ul><li>Slowing down is also considered acceleration! It is called negative acceleration . </li></ul><ul><li>Formula: (final velocity – initial velocity) </li></ul><ul><li>time </li></ul>
6. 6. 5. Graphing Acceleration: velocity over time <ul><li>Section A: acceleration </li></ul><ul><li>Section B: no acceleration; constant velocity </li></ul><ul><li>Section C: negative acceleration </li></ul>
7. 7. 6. Newton’s Laws of Motion <ul><li>To understand Newton’s Laws: </li></ul><ul><li>Force: a push or pull with a size and direction. </li></ul><ul><ul><li>Balanced forces: 2 forces that are equal but in opposite directions, canceling each other out. </li></ul></ul><ul><ul><li>Unbalanced forces: when one force is greater than another, causing a change in motion. </li></ul></ul><ul><li>Measured in newtons, N . </li></ul>
8. 8. 7. 1 st Law of Motion <ul><li>Objects resist changes in motion! </li></ul><ul><ul><li>If an object is at rest, it will stay at rest* </li></ul></ul><ul><ul><li>If an object is in motion, it will stay in motion* </li></ul></ul><ul><ul><ul><li>*Unless acted on by a force! </li></ul></ul></ul><ul><li>Also known as: The Law of Inertia </li></ul><ul><ul><li>More mass = more inertia </li></ul></ul>
9. 9. 8. 2 nd Law of Motion <ul><li>An object acted on by an unbalanced force will accelerate in the direction of the force. </li></ul><ul><ul><li>Mass (m) & Acceleration (a) affect force (F). </li></ul></ul><ul><ul><li>Formula: F = ma </li></ul></ul><ul><ul><li>When falling, acceleration is due to gravity and is a constant: 9.8 m/s 2 </li></ul></ul>
10. 10. 9. 3 rd Law of Motion <ul><li>For every action, there is an equal but opposite reaction. </li></ul><ul><ul><li>When a force is exerted on an object, the object exerts the same amount of force. </li></ul></ul>
11. 11. 10. Force of Gravity: Mass V. Weight <ul><li>B. Mass </li></ul><ul><ul><li>The amount of matter an object has, regardless of any outside force being applied. </li></ul></ul><ul><ul><li>On the Moon, your mass would remain the same, but your weight would change. </li></ul></ul><ul><li>C. Weight </li></ul><ul><ul><li>The force of gravity multiplied by mass. </li></ul></ul><ul><ul><li>An object’s weight can change, depending on the pull of gravity. </li></ul></ul><ul><ul><li>On Earth, it’s calculated as mass X 9.8 m/s 2 </li></ul></ul><ul><ul><li>Measured in Newtons. </li></ul></ul><ul><li>Gravity: the force of attraction that exists between any two objects that have mass. </li></ul>
12. 12. 11. Friction: A. a force that resists motion & is always present between 2 moving surfaces <ul><li>Rolling friction: friction between a surface and a wheel as the wheel rolls. </li></ul><ul><li>Sliding friction: friction that occurs when 2 surfaces slide past each other, slowing down the moving object. </li></ul><ul><li>Static friction: Friction that hinders a stationary object from moving on a surface when a force is applied. </li></ul>
13. 13. 12. Air Resistance: A special form of Friction <ul><li>Why does the feather fall more slowly than the elephant? </li></ul><ul><ul><li>Acceleration due to gravity is constant at 9.8 m/s 2 ; therefore, the elephant should hit with a stronger force, but not faster. </li></ul></ul><ul><ul><li>The action of air molecules ‘catch’ on the surface area of an object and slow it down. </li></ul></ul><ul><ul><li>According to Galileo, without air resistance, both objects would hit the ground at the same time! </li></ul></ul>
14. 14. B. Galileo proved right! <ul><ul><li>While on the Moon, the Apollo astronauts proved Galileo correct. </li></ul></ul><ul><ul><li>Although they dropped a hammer, not an elephant, the two objects landed at the same time. </li></ul></ul><ul><li>C. Acceleration due to gravity is a constant – 9.8 m/s 2 </li></ul><ul><li>Acceleration is not affected by the mass of the object! </li></ul><ul><li>(but slowing down is effected by air resistance) </li></ul>
15. 15. Special note: <ul><li>Answer to number 6 on page 22:postiive </li></ul>