DISTANCE/DISPLACEMENTPOSITION GRAPH VS. TIME

Physics

Mr.Villa

From last time…………

Distance is……..Displacement is…….Speed is……..Velocity is……..

From last time……….

A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North.

What is the total distance? 12 meters What is the total displacement? 0 meters. Started and finished in the same

spot.

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From last time……….

A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North. All this, done in 24 seconds.

What is the avg. speed? 0.50 m/s What is the avg. velocity? 0 m/s. 0 displacement/24 seconds =0

W E

Graphing Linear Motion

There are three different types of linear motion graphs that we will by analyzing. Displacement vs. Time

Describes how an objects position is changing over time

Velocity vs. TimeDescribes how an objects velocity is changing over time

Position-Time Graphs

Show an object’s position as a function of time.

x-axis: time y-axis: position

Position-Time Graphs

Imagine a ball rolling along a table, illuminated by a strobe light every second.

You can plot the ball’s position as a function of time.

0 s

1 s

2 s

3 s

4 s

5 s

6 s

7 s

8 s

9 s

10 s

Position-Time Graphs

1 2 3 4 5 6 7 8 9 10

1

2

3

4

5

6

7

8

9

10

time (s)

posi

tion

(cm

)

Displacement vs. Time

The slope of the line at any given point will equal the velocity of the object at that point. Straight flat line → no movement Straight non-flat line → constant velocity (no acceleration)

Curved line → accelerating velocity

Example 1

The displacement-time graph for a tennis ball which is thrown vertically up in the air from a player’s hand and then falls to the ground.

Example 2

A bus travels along a straight road for 600 m. It travels at a constant velocity for the whole journey, which takes 90 s. Sketch the displacement-time graph. What was the velocity of the bus?

Examples

Draw a displacement vs. time graph for the following: A tennis ball bouncing up and down

Examples

Draw a displacement vs. time graph for the following: A track star running the 400 m

Examples

Draw a displacement vs. time graph for the following: A baseball thrown up and then caught again

Examples

Draw a displacement vs. time graph for the following: A baseball thrown up and then allowed to hit the ground

Velocity vs. Time

The slope of the line at any given point equals the objects acceleration at that point. Straight flat line → no acceleration

(constant speed) Straight non-flat line → constant

acceleration Curved line → increasing/decreasing

acceleration The area under the line equals the

displacement of the object up to that point.

From last time……..