Distance-Time Graphs

Distance-Time Graphs Overview

• Distance-Time graphs visually represent the motion of an object over a specific period of time.
• The horizontal (x) axis represents time and the vertical (y) axis represents distance.
• A straight, horizontal line on a distance-time graph indicates the object is stationary. It is not moving because the distance does not change over time.
• An upwards sloping line means the object is moving. The steeper the line, the faster the object is moving.
• A downwards sloping line is not common in distance-time graphs as it would imply that the object is moving backwards.

Reading Distance-Time Graphs

• The slope of the graph gives the speed of the object.
• Modify the scale of the axes if required, to make it easier to calculate the speed.
• Measure the vertical and horizontal distances on the graph to determine the speed using the formula speed = distance/time.
• Find the time for which the object is stationary by identifying the periods where the graph is a horizontal line.
• Identify periods of constant speed by spotting straight, slanted lines.
• More complex motion, such as acceleration, is represented by a curved line.

Calculating Speed from Distance-Time Graphs

• Calculate speed by using the formula speed = distance/time.
• To extract this data from a graph, select two points on the straight line of the graph and use their coordinates to calculate the rise (distance) over run (time).

Drawing Distance-Time Graphs

• Given a table of distances and times, plot the points onto the graph accordingly.
• Create horizontal lines for times during which the object doesn’t move.
• Create straight, sloping lines for times when the object moves at a constant speed.
• Ensure to choose an appropriate scale for the axes for precise graph plotting and reading.
• Check your graph by verifying that the object’s speed matches the slope of the graph.