A man stands before a train. We noticed that after 2seconds the first wagon has passed. How many seconds are needed for the 16th wagon to pass?

Question

A man stands before a train. We noticed that after 2 seconds the first wagon has passed. How many seconds are needed for the 16th wagon to pass? The speed is constant

Answer 1

Hi Sarah from New York, NY...hope you had a great day at school.

This is a great question...I'm going to help you set it up, however, I won't give you the answer. One reason is that there are 2 small important facts left out, which I presume your teacher is expecting you to assume.

First item: is the train at a constant speed

Second item, what is the distance between each of the wagons? 

I am sure you teacher has given you the information to address those issues. Much like if someone is asked to calculate the speed and time it would take an object to move along a surface, we'd have to take into account the issue of 'friction'. There is actually a constant which needs to be included when making these kinds of calculations.

With that said, if each wagon passes completely in 1 second, then we can assume that since there are 16 wagons, then it would be 16 seconds for the train to pass, 

Reasoning, 1st wagon...passes in 1 second, 2nd wagon takes another second to pass, so the that would be 2 seconds total, and so on the the 3rd, 4th, 5th...etc.

However, like I states, is the train moving at constant speed?

Is there a distance between each of the wagons? How would you include that in your equation in calculating the total time for the 16th wagon to pass. Here is my hint: let t equal the amount of time it takes for each wagon to pass and w equal the number of wagons in the train. Then we could[if your teacher wants you to] include the value of distance between each wagon, which could add a fraction of time for the next wagon to pass by completely. Then adding up all those values, it would add to the total amount of time for the 16th wagon to pass.

Like I said, I won't answer it for you, but help you work toward understanding what you teacher is asking you to understand when addressing these kind of problems.

Let me know how it works out. Contact me on Wyzant.