Distance-time graphs

You should be able to draw and explain distance-time graphs for objects moving at steady speeds or standing still.

Background information

The vertical axis (y-axis) of a distance-time graph is the distance traveled from the start. The horizontal axis (x-axis) is the time from the start.

Features of the graphs

When an object is stationary, the line on the graph is horizontal. When an object is moving at a steady speed, the line on the graph is straight, but sloped.

The diagram shows some typical lines on a distance-time graph.

Distance -time Note that the steeper the line, the greater the speed of the object. The blue line is steeper than the red because it represents an object moving faster than the one represented by the red line. The red lines on the graph represent a typical journey where an object returns to the start again. Notice that the line representing the return journey slopes downwards.

Speed can be calculated from Distance-Time graph using the formula

speed=distance/time

or slope of the graph gives the speed of the object/body.

Velocity-time graphs

You should be able to explain velocity-time graphs for objects moving with a constant velocity or constant acceleration.

Background information

The velocity of an object is its speed in a particular direction. This means that two cars traveling at the same speed, but in opposite directions, have different velocities.

The y– axis of a velocity-time graph is the velocity of the object. The x– axis is the time from the start.

Features of the graphs

When an object is moving with a constant velocity, the line on the graph is horizontal. When an object is moving with a constant acceleration, the line on the graph is straight, but sloped. The diagram shows some typical lines on a velocity-time graph.

time speed graph

The steeper the line, the greater the acceleration of the object. The blue line is steeper than the red line because it represents an object with a greater acceleration.

Notice that a line sloping downwards – with a negative gradient – represents an object with a constant deceleration – slowing down.

Distance traveled by the body can be calculated from Speed-Time/(Velocity-Time) graph using the formula

Distance=speed×time

which means Area under the graph.

Look at the shape/region under the graph and use the Geometric formula to find the area.