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ACCELERATION: C10,S2

ACCELERATION: C10,S2. ACCLELERATION DEFINITION. the rate at which velocity changes (includes: speeding up, slowing down, or changing directions). POSITIVE ACCELERATION. Speeding up; also called accelerating. NEGATIVE ACCELERATION.

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ACCELERATION: C10,S2

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  1. ACCELERATION: C10,S2

  2. ACCLELERATION DEFINITION the rate at which velocity changes (includes: speeding up, slowing down, or changing directions)

  3. POSITIVE ACCELERATION • Speeding up; also called accelerating

  4. NEGATIVE ACCELERATION • Slowing down; also called deccelerating

  5. CHANGE of DIRECTION • Turning, which is a change of direction, is also acceleration

  6. FORCE of ACCELERATION • Acceleration is always caused by a force (a push or a pull on something). • For example: • What force causes a bicycle to stop? • Friction caused by brakes pushing on tires • Friction caused by tires pushing on road

  7. FORCE of ACCELERATION, continued… B) What force causes a car to turn? - Friction pushing against the side of the tires.

  8. FORCE of ACCELERATION, continued… C) What force causes a rocket to take off? - The force of the exhaust gases pushing out the bottom of the rocket.

  9. FORMULA of ACCELERATION

  10. SI Units of ACCELERATION m/s/s or m/s2 or even… km/h/s ** This is because you are dividing speed (m/s or km/h) by time (s)

  11. EXAMPLE - #1 SOLVE FOR ACCELERATION: 15 km/hr 20 km/hr 5 km/hr 10 km/hr 25 km/hr 0 km/hr 0 sec 3 sec 5 sec 1 sec 2 sec 4 sec The acceleration of a motorcycle is 5 km/hr/sec (every second, the motorcycle will increase its speed by 5 km/hr)

  12. EXAMPLE #2 A man jumps from a plane. His beginning speed is 100 km/hr SE (southeast), and his final speed with his parachute is 10 km/hr SE (southeast). This took 3 sec. What was his acceleration? SOLVE FOR ACCELERATION: a = ? Sf= 10km/hr Ss= 100km/hr t = 3s a = Sf – Ss t a = (10 km/hr – 100 km/hr) 3s = -90km/hr 3s = -30km/hr/s The negative sign means that he was decelerating (slowing down).

  13. ACCELERATION REVIEW #1 1) A change in velocity (or speed) divided by the time it takes for the change to occur equals the object’s _______.

  14. ACCELERATION REVIEW #2 2) Imagine yourself driving a car down an empty stretch of road. Describe 3 ways you could you change your acceleration.

  15. ACCELERATION REVIEW #3 3) Calculate the acceleration of a bus whose speed changes from 6m/s to 12m/s over a period of 3s.

  16. ACCELERATION REVIEW #1 ANSWER: 1) The answer is acceleration. Remember that, like velocity, acceleration has a direction. A car that takes a turn has changed its acceleration, even if nothing else changes.

  17. ACCELERATION REVIEW #2 ANSWER: 2) You could step on the gas; you could also step on the brake; you could turn the wheel, or do any combination of these.

  18. ACCELERATION REVIEW #3 ANSWER: Calculate the acceleration of a bus whose speed changes from 6m/s to 12m/s over a period of 3s. a = ? Sf= 12m/s Ss= 6m/s t = 3s a = Sf – Ss t a = (12 m/s – 6 m/s) 3s = 6m/s 3s = 2 m/s/s

  19. PART 2 Interpreting Graphs

  20. Reading Graphs of Acceleration • You can represent the acceleration of an object with a speed-time graph • speed is plotted on the vertical axis (y) • time is plotted on the horizontal axis (x)

  21. Reading Graphs of Acceleration • An object that is speeding up will have a line that slopes upward (Ex. A)

  22. Reading Graphs of Acceleration • An object that is slowing down will have a line that slopes downward (Ex. C)

  23. Reading Graphs of Acceleration • A horizontal line represents an acceleration of zero or constant speed (Ex. B)

  24. Copy Graph Below and Label

  25. ACCELERATION REVIEW #4 4) When reading an acceleration graph, what variable will you find on the y-axis? On the x-axis? HINT: a = Sf – Ss t

  26. ANSWER #4 SPEED (y-axis) & TIME (x-axis) a = Sf – Ss t

  27. ACCELERATION REVIEW #5 5) What is happening at point Ain this speed-time graph? A. the object is speeding up B. the object is slowing down C. the object is at rest D. the object has a constant speed

  28. ANSWER #5 Point A = object is speeding up LABEL THIS ON YOUR GRAPH

  29. ACCELERATION REVIEW #6 6) What is happening at point Bin this speed-time graph? A. the object is speeding up B. the object is slowing down C. the object is at rest D. the object has a constant speed

  30. ANSWER #6 Point B = object has a constant speed LABEL THIS ON YOUR GRAPH

  31. ACCELERATION REVIEW #7 7) What is happening at point Cin this speed-time graph? A. the object is speeding up B. the object is slowing down C. the object is at rest D. the object has a constant speed

  32. ANSWER #7 Point C = object is slowing down LABEL THIS ON YOUR GRAPH

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