Displacement-Time Graphs Kinematics

Distance Time Graphs The slope of a distance time graph will tell us the velocity of the object. There are 3 possible cases:

1. Horizontal Line Slope of this line is zero. The speed is If your speed is zero you are NOT MOVING.

2. Uphill Line Slope of this line is POSITIVE. If your speed is positive you are MOVING FORWARD (or North, etc).

3. Downhill Line Slope of this line is NEGATIVE. If your speed is negative you are MOVING BACKWARD.

Match the Graph to the Description 1. The car is stopped. 2. The speed of the car is decreasing. 3. The car is coming back at a constant speed.

Uniform Motion What you studied in Science 10 Only straight lines when graphed Constant velocity (although we can look at graphs/situations where the velocity changes for different sections of the graph)

Velocity: position (Δdisplacement) vs Velocity: position (Δdisplacement) vs. time graphs Consider a car moving with a constant, rightward (+) velocity of +10 m/s. If the position-time data for such a car were graphed, then the resulting graph would look like the graph at the right. Note that a motion described as a constant, positive velocity results in a line of constant and positive slope when plotted as a position-time graph. This is uniform motion!!!

The slope of a position-time graph is the velocity

Calculating average velocity from a position-time graph: Each section of the graph has a different slope. Velocities can be calculated by finding individual slopes of that section. The average velocity of the total graph or trip is found by using the beginning and end points only.

Finding velocities

What is happening here?

What is happening here?

1) On one graph draw the following: A: an object that is stationary and behind the starting line. B: an object that is stationary and in front of the starting line. C: an object that is stationary and at the starting line.

A: red B: blue C: purple These are only examples. Your graph may be different.

2) On one graph draw the following: A: an object that is moving in a positive direction and starts behind the starting line. B: an object that is moving in a positive direction and starts at the starting line. C: an object that is moving in a positive direction and starts in front of the starting line. D: an object that is moving in a positive direction but faster than the first object (starting at the starting line) E: an object that is moving in a positive direction but slower than the first object (starting in front of the starting line)

A: red B: blue C: purple D: green E: orange These are only examples. Your graph may be different.

3) On one graph draw the following: A) an object that is moving in a negative direction and starts behind the starting line. B) an object that is moving in a negative direction but faster than the first object and starts at the starting line. C) an object that is moving in a negative direction but slower than the first object and starts in front of the starting line.

A: red B: blue C: purple These are only examples. Your graph may be different.

Answers A) 2.5 m above starting point or right of starting point (you need an origin!) B) At the starting point. C) -1 m D) d = d1 + d2 = 3 + 4 = 7 m