KINEMATICS IN ONE DIRECTION

PERIOD #2 NOTES ON GRAPHS

Graphing Review From Physics 11

• The dependent variable is plotted on the y-axis.
• The independent variable is plotted on the x-axis.
• The title of the graph should indicated what type of graph it is and what the graph is about. For example - a graph of a woman walking a distance over a period of time would be called "position-time graph of woman walking".
• The slope of the graph illustrates how fast the dependent variable is changing relative to how fast the independent variable is changing. The steeper the slope the faster the dependent variable is changing relative to the independent variable.

slope   =   rise   =  D y   =  y₂ - y₁

       run      D x        x₂ - x₁

• The slope of a position-time graph is velocity.
• A straight line on a position-time graph represents uniform velocity.
• The slope of a straight line between any two points is the average velocity for that time period.
• The slope of a tangent to a point on a curve is the instantaneous velocity at that point in time.
• Positive slope means that the object is travelling in a given direction, while a negative slope would indicate that the object is travelling a direction opposite to the given one.
• The slope of a velocity-time graph is acceleration.
• A straight line on a velocity-time graph represents uniform acceleration.
• The area under a velocity-time graph is equal to the displacement of the object.
• The slope of a straight line between any two points is the average acceleration for that time period.
• The slope of a tangent to a point on a curve is the instantaneous acceleration at that point in time.
• A positive slope means that the object is accelerating in the given direction whereas a negative slope indicates that the object is accelerating in the opposite direction.

Addition Requirements

Please observe the following guidelines for constructing graphs. Two example graphs are provided for reference.

1. As a title, all graphs should have the experiment number, the title of the experiment and the relationship written out in full with appropriate units.

2. Axis titles should be written in full with the appropriate units.

3. Simple scales that take up most of the graph paper should be used.

4. The correct number of significant figures should be used on both scales.

5. Draw only one graph per page.

6. Plotted points should be small, and each point circled.

7. The coorinates of each point should not be put on the graph.

8. When appropriate, slope calculations should be shown on the graph with appropriate units after each figure.

9. Linear graphs should always be drawn with the best fit straight line. Use a plastic ruler to help you find it.

10. Non-linear graphs should be drawn carefully with a smooth curve.