Reading Motion Graphs

Reading Motion Graphs (velocity and acceleration)

Position vs time

Velocity vs time

This graph shows an object is not moving.

The vertical axis shows position. Is the position changing over time? No, the object is in the same position. If there is no change in position, the object is not moving.

This graph shows an object moving.

The vertical axis shows position. Is the position changing over time? Yes, it is. So this shows a moving object. This line is straight so the rate of change is constant. Every second the object moves the same amount

Does this graph show an object that is stopped?

No, this object is moving. If you look at the vertical axis it shows velocity, not position. The flat line here shows something is not changing, but it is the velocity that is not changing. The velocity is not zero so the object is moving.

This graph shows one fast object and one slow object.

The vertical axis shows position. Both lines show a change in position. The red line shows a larger change in position in a shorter period of time. The Green line takes more time to cover a shorter distance.

The red line shows a faster rate of motion than the green line.

This graph shows one fast object and one slow object also.

The red line shows a constant velocity that is greater then the constant velocity of the green line. A flat line does not alway mean stopped, it means what ever is on the vertical axis is not changing.

Both of these objects are stopped.

Since the vertical axis shows position, these flat lines show the positions are not changing, they are both stopped. The red line shows an object stopped a greater distance from the reference point than the green line.

When reading graphs you have to look at the values on both the vertical axis and the horizontal axis.

You cannot just look at the line or lines. Now try to answer some questions about motion graphs.

Multiple Choice

Which graph shows an object that is not moving

Multiple Choice

Which graph show a fast object

Multiple Choice

This graph has velocity on the vertical axis. The flat line means

• The velocity is changing

• The velocity is not changing

• The object is not moving

Multiple Choice

Which graph show an fast moving object

Multiple Choice

Which graph shows an object that is not moving.

• Both graphs

• Neither graph