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Hold down the T key for 3 seconds to activate the audio accessibility mode, at which point you can click the K key to pause and resume audio. Useful for the Check Your Understanding and See Answers.

Fundamentals

The speed of an object refers to how fast it is moving. It is equal to the distance per time ratio for the motion. Using this relationship, one can calculate the distance, the time, or the average speed if the two other quantities are known.

For a changing speed motion that occurs at a uniform rate, the average speed is the average of the initial and the final speed. 
 

There are three similar versions of this question. Each version displays eight numerical items on a 3x3 grid of squares. The location of each item on the grid is randomly chosen. Here is one of those versions:
 

Version 1:

Steadily speeds up from rest to 8 m/s in 2 s.
After moving more than 4 s, has a final speed of 8 m/s.
Travels 8 m.
Starts at rest and travels 32 m for 8 s.
Travels 16 m in 4 s.
Travels 16 m in 2 s.
Has a constant speed of 4 m/s.
Averages a speed of 8 m/s.

How to Think About This Situation

To be successful with this Difficulty Level you will need to perform two types of calculations and recognize a huge concept:

1) You will need to calculate the average speed of an object from its distance traveled and its time of travel. Dividing distance by time yields the value for average speed.

2) You will need o calculate the distance traveled from the time of travel and the average speed. Multiplying the average speed by the time yields the distance traveled.

3)  HUGE Concept: For an object that changes its velocity at a uniform rate, the average speed is simply the average of the initial speed and the final speed. The average speed value lies exactly in the middle of the initial speed value and the final speed value.
 

Try this link to The Physics Classroom Tutorial for more help with the concept of speed and its relationship to distance and time:

Speed and Velocity
 

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