 # The graphs Part II…. The slope of a position vs time graph is? The slope of part 1? The slope of part 2? The velocity in interval 3? Velocity + 2 m/s.

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The graphs Part II…

The slope of a position vs time graph is? The slope of part 1? The slope of part 2? The velocity in interval 3? Velocity + 2 m/s -1m/s

Consider a car moving with a constant, rightward (+) velocity of +10 m/s. What does a velocity vs time graph look like for this motion? Zero Acceleration

Now consider a car moving with a rightward (+), changing velocity – that is, a car that is moving rightward and speeding up or accelerating. The car is moving in the positive direction and speeding up, it is said to have a positive acceleration. And the graph?

The instantaneous acceleration of an object at a certain time is the slope of the velocity versus time graph at that time. It can be positive, negative, or zero. The slope of a velocity time graph is … Slope = Δy = Change in velocity = Δx Change in time ACCELERATION

Positive and negative acceleration & velocity? Acceleration and velocity are in opposite directions Acceleration and velocity in same direction Acceleration and velocity are in opposite directions

9/17 Pick up both sheets on front and work on these in class. I will be passing around a class roster. Please sign your name to indicate that you have received your progress report Remember you will turn in WS 3,4 5,& 6 tomorrow. Skip 4, 6-9 on WS 3 Skip 4 on WS 4

What would a d vs t graph look like if a ball was thrown up into the air? How would you describe each phase of motion ie. Displacement, velocity, acceleration? What would this look like on a v vs t graph? On an acceleration graph?

What would a d vs t graph look like if a ball was thrown up into the air? How would you describe each phase of motion ie. Displacement, velocity, acceleration? What would this look like on a v vs t graph? On an acceleration graph? D v T V v T A v T

Summary for dots! On a V vs T graph: Velocity is + in Quad 1 (top) Velocity is - in Quad 4 (bottom) Acceleration is + if slope is + Acceleration is - if slope is -

Describe the motion of the dot. What does the position vs time graph look like? What does the velocity vs time graph look like? What does the acceleration vs time graph look like? Constant positive velocity

Describe the motion of the dot. What does the position vs time graph look like? What does the velocity vs time graph look like? What does the acceleration vs time graph look like? A negative constant velocity

Describe the motion of the dot. What does the position vs time graph look like? What does the velocity vs time graph look like? What does the acceleration vs time graph look like? A positive velocity and a positive acceleration

Describe the motion of the dot. What does the position vs time graph look like? What does the velocity vs time graph look like? What does the acceleration vs time graph look like? A positive velocity and negative acceleration

Describe the motion of the dot. What does the position vs time graph look like? What does the velocity vs time graph look like? What does the acceleration vs time graph look like? A negative velocity and negative acceleration

Example: The velocity-time graph for a two-stage rocket is shown below. Use the graph and your understanding of slope calculations to determine the acceleration of the rocket during the listed time intervals 0 to 1 sec 1 to 4 sec4 to 9 sec9 to 12 sec + 40m/s 2 accelerating upward +20 m/s 2 Still accelerating upward -20 m/s 2 Decelerating & moving upward -20 m/s 2 Accelerating downward

3,2,1,Blast off…

Example 2: a) What is the acceleration in interval A? Acc = Δy = (20 – 0 m/s) = Δx (10 – 0 s) + 2 m/s 2 b) What distance does it travel in first the 20s? The distance covered is the “area under” the line. Area = ½ bh Distance = ½ (20s)(40m/s) Distance = 400 m

Example 2: The distance covered is the “area under” the line. c) What is the acceleration in interval B? Constant velocity of +40 m/s d) What is the distance traveled during t=20s to t = 40s? Area = (b)(h) Distance = (20s)(40m/s) Distance = 800m e) What is the total distance? Distance = 400m + 800m = 1200m

Classwork: Graphing Little Dudes WS # 2

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