Question 1184116: George walks to a friend's house. He walks 750 meters North, then realizes he walked too far. He turns around and walks 250 meters South. The entire walk takes him 13 seconds. What is his speed per second?
What was Demetrius’s velocity in meters per second?
Found 3 solutions by josgarithmetic, ikleyn, greenestamps:
Answer by josgarithmetic(39615)   (Show Source):
Answer by ikleyn(52765)  (Show Source):
You can put this solution on YOUR website! .
(1) The literal meaning of the term "velocity" is an "instant velocity", in distinction from the notion of the "average velocity".
(2) Velocity is a vector, and in the given problem, it varies : it is DIFFERENT at different parts of the trip (has different sign).
So, the question related to velocity in this problem, does require further clarifications in order for it would be
(would become) meaningful.
In whole, this problem, as it is worded and presented, is more a puzzle than a Math problem.
// And this last notice equally relates to many  of other problems,
that unprofessional "Math problem composers" create and post at this forum.
Answer by greenestamps(13198)  (Show Source):
You can put this solution on YOUR website!
As the other tutors who responded both said, the statement of the problem does not allow us to answer the questions.
"speed" and "velocity" are both measurements at a specific time; there is nothing in the statement of the problem that tells us anything about his speed or velocity at any one time.
Note also that "speed per second" is a nonsensical phrase....
The intent of the problem is clearly to determine the AVERAGE speed and the AVERAGE velocity, and presumably to explain the difference between the two.
For average speed, he traveled 750+250=1000 meters in 13 seconds; his average speed was 1000/13 meters per second.
For average velocity, the calculation is the total displacement divided by the time. Since he ended up only 500 meters from his starting point, his average velocity was 500/13 meters per second.
NB.... 1000 meters in 13 seconds is a rather fast "walk"....!
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