ACCELERATION C 10 S 2 1 ACCELERATION DEFINITION

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ACCELERATION: C 10, S 2 1

ACCELERATION: C 10, S 2 1

ACCELERATION DEFINITION the rate at which velocity changes (includes: speeding up, slowing down, or

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

POSITIVE ACCELERATION ØSpeeding up; also called accelerating 3

POSITIVE ACCELERATION ØSpeeding up; also called accelerating 3

NEGATIVE ACCELERATION ØSlowing down; also called deccelerating 4

NEGATIVE ACCELERATION ØSlowing down; also called deccelerating 4

CHANGE of DIRECTION ØTurning, which is a change of direction, is also acceleration 5

CHANGE of DIRECTION ØTurning, which is a change of direction, is also acceleration 5

FORCE of ACCELERATION • Acceleration is always caused by a force (a push or

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

FORCE of ACCELERATION, continued… B) What force causes a car to turn? - Friction

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

FORCE of ACCELERATION, continued… C) What force causes a rocket to take off? -

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. 8

FORMULA of ACCELERATION

FORMULA of ACCELERATION

SI Units of ACCELERATION 2 m/s/s or or even… km/h/s ** This is because

SI Units of ACCELERATION 2 m/s/s or or even… km/h/s ** This is because you are dividing speed (m/s or km/h) by time (s) 10

EXAMPLE - #1 0 km/hr 0 sec 5 km/hr 10 km/hr 1 sec 2

EXAMPLE - #1 0 km/hr 0 sec 5 km/hr 10 km/hr 1 sec 2 sec 15 km/hr 3 sec 20 km/hr 25 km/hr 4 sec 5 sec SOLVE FOR ACCELERATION: 11

EXAMPLE #2 A man jumps from a plane. His beginning speed is 100 km/hr

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 – S s t a=? Sf= 10 km/hr Ss= 100 km/hr t = 3 s a = (10 km/hr – 100 km/hr) = -90 km/hr = -30 km/hr/s 3 s 3 s The negative sign means that he was decelerating (slowing down). 12

ACCELERATION REVIEW #1 1) A change in velocity (or speed) divided by the time

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 _______. 13

ACCELERATION REVIEW #2 2) Imagine yourself driving a car down an empty stretch of

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

ACCELERATION REVIEW #3 3) Calculate the acceleration of a bus whose speed changes from

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

ACCELERATION REVIEW #1 ANSWER: 1) The answer is acceleration. Remember that, like velocity, acceleration

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. 16

ACCELERATION REVIEW #2 ANSWER: 2) You could step on the gas; you could also

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. 17

ACCELERATION REVIEW #3 ANSWER: Calculate the acceleration of a bus whose speed changes from

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

PART 2 Graphing Acceleration 19

PART 2 Graphing Acceleration 19

Graphing Acceleration • You can represent the acceleration of an object with a speed-time

Graphing 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)

Graphing Acceleration • An object that is speeding up will have a line that

Graphing Acceleration • An object that is speeding up will have a line that slopes upward (Ex. A)

Graphing Acceleration • An object that is slowing down will have a line that

Graphing Acceleration • An object that is slowing down will have a line that slopes downward (Ex. C)

Graphing Acceleration • A horizontal line represents an acceleration of zero or constant speed

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

Copy Graph Below and Label

Copy Graph Below and Label

ACCELERATION REVIEW #4 4) To graph acceleration, what variable would you put on the

ACCELERATION REVIEW #4 4) To graph acceleration, what variable would you put on the y -axis? On the x-axis? HINT: a = Sf – S s t 25

ANSWER #4 SPEED (y-axis) & TIME (x-axis) a = Sf – S s t

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

ACCELERATION REVIEW #5 5) What is happening at point A in this speed-time graph?

ACCELERATION REVIEW #5 5) What is happening at point A in 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 27

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

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

ACCELERATION REVIEW #6 6) What is happening at point B in this speed-time graph?

ACCELERATION REVIEW #6 6) What is happening at point B in 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 29

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

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

ACCELERATION REVIEW #7 7) What is happening at point C in this speed-time graph?

ACCELERATION REVIEW #7 7) What is happening at point C in 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 31

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

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