1-D Kinematics: Graphing Velocity

1-D Kinematics: Graphing Velocity

Interpreting Motion from Velocity Graphs

Velocity vs Time Graphs

• constant positive slope = acceleration

• no slope = moving at a constant rate

• constant negative slope = slowing down

• changing slope = increasing or decreasing acceleration

Calculating Acceleration from V vs t Graphs

• Slope of V vs t Graph = Acceleration

• Slope (m) = Rise / Run = (y2-y1)/(x2-x1)

• What would be the acceleration of this object?

• Pick 2 coordinate sets.

• (x1,y1)(x2,y2).....(0,0)(4,8)

• Plug into slope equation....

• m = (8-0)/(4-0) = 8/4 = 2 m/s/s (units for V on graph are wrong)

Fill in the Blanks

What is the acceleration of the object that is speeding up? (include units)

Fill in the Blanks

What is the acceleration of the object that is slowing down? (include units in your answer)

What if graph crosses the x axis into negative territory???

• the sign on velocity just represents direction

• (+) velocity = object traveling right or up.

• (-) velocity = object traveling left or down.

• so if a Velocity vs time graph crosses the X axis it just means the object is changing direction.

Determine displacement from a Velocity vs time Graph

• Displacement on a Velocity vs time Graph = AREA UNDER THE GRAPH

• Divide up area under the graph into rectangles and triangles.

• Find area of each and add together.

• Area of triangle = 1/2(b*h)

• Area of rectangle = l*w

Fill in the Blanks

What is the distance travelled by the object that made this graph? (include units in your answer)

Fill in the Blanks

What is the distance travelled by the object that made this graph? (include units in your answer)

What if its a CURVE???

• You need calculus to solve!

• This is a CP class so we will stick to constant slopes!

That's the END of Section 1

(Describing Motion using Graphs)