Motion Graphs

Motion Graphs

 Motion Graphs

Describing the motion of an object is occasionally hard to do with words. Sometimes graphs help make motion easier to picture, and therefore understand.

Remember:

• Motion is a change in position measured by distance and time.

• Speed tells us the rate at which an object moves.

• Velocity tells the speed and direction of a moving object.

• Acceleration tells us the rate speed or direction changes.

Distance - Time Graphs

Let's take a look!

If an object is not moving, a horizontal line is shown on a distance-time graph.  

If an object is moving at a constant speed, it means it has the same increase in distance in a given time.

Let’s look at two moving objects: Both of the lines in the graph show that each object moved the same distance, but the steeper dashed line got there before the other one.

Graphs that show acceleration look different from those that show constant speed.  

Summary

• A distance-time graph tells us how far an object has moved with time.

• The steeper the graph, the faster the motion.

• A horizontal line means the object is not changing its position - it is not moving, it is at rest.

• A downward sloping line means the object is returning to the start. 

Multiple Choice

In which of the following graphs below are both runners moving at the same speed? *Look at which graph is which. They are labeled A, B, D, C.*

• Graph A

• Graph B

• Graph D

• Graph C

Speed - Time Graphs

Speed-Time graphs are also called Velocity-Time graphs.  

Summary

• A speed - time graph shows us how the speed of a moving object changes with time.

• The steeper the graph, the greater the acceleration.

• A horizontal line means the object is moving at a constant speed.

• A downward sloping line means the object is slowing down. 

Multiple Choice

Which runner stopped for a rest?

• Albert

• Bob

• Charlie

Multiple Choice

Look at the graph above. It shows how three runners ran a 100-meter race. Which runner won the race?

• Albert

• Bob

• Charlie

Multiple Choice

When an object is not moving, it is referred to as:

• acceleration

• deceleration

• at rest

• constant speed

Multiple Choice

The time can be found on:

• the x-axis

• the y-axis

Multiple Choice

A dashed line on a speed time graph represents:

• deceleration

• acceleration

• a greater acceleration

• a greater deceleration