# The point of no return

• Aug 9th 2008, 04:05 PM
hungrybarts
The point of no return
http://img375.imageshack.us/img375/1...oreturnqv0.jpg

Thanks for your attention, appreciate it.
• Aug 9th 2008, 07:20 PM
mr fantastic
Quote:

Originally Posted by hungrybarts
http://img375.imageshack.us/img375/1...oreturnqv0.jpg

I have absolutely no idea about this. Can you give me a step by step solution? Mr F says: You want to be given a step-by-step solution to an assessment task (Speechless) Do the words academic fraud mean anything to you? I will give you some help with question 1 (see main post) - then you're on your own.
Thanks for your attention, appreciate it.

Let d be distance from the air field and t be time flying.

On an appropriate set of axes, draw the line d = 350 t (where has the 350 come from?) but stop at a point. Label that point (d1, t1). t1 is the time flown with the wind. What is the relationship between d1 and t1 (you will need this relationship)?

Now draw a line from the point (d1, t1) to the point (0, 4) (where has the 4 come from?) What must the slope of this line be? Use the value of this slope to help calculate a value of t1.

• Aug 10th 2008, 11:47 PM
hungrybarts
my apologize for that mr fantastic but apparently, no one in my class is able to solve this so, should the distance be on the y-axis and the time be on the x-axis (distance against time)? and i still don't get how to do no 1
• Aug 11th 2008, 02:54 AM
mr fantastic
Quote:

Originally Posted by hungrybarts
my apologize for that mr fantastic but apparently, no one in my class is able to solve this so, should the distance be on the y-axis and the time be on the x-axis (distance against time)? Mr F says: Yes.

and i still don't get how to do no 1 Mr F says: Now try doing what I suggested in my first post.

..
• Aug 11th 2008, 03:25 AM
Logic
Hello,
I believe I can answer the question. However, as I understand a "hint" is given to help someone, but its usage is not imperative. I have so decided to disregard the graph hint and thought up another solution, whose correctness I cannot guarantee.

My idea is the following:
We are looking for a maximum distance which we can travel given the circumstances and come back.
So let S1 be the distance we are travelling forward, V1 - the going-forward speed, t1 - the time we are travelling forward and S2, V2, t2 - the same variables only that when we are travelling back.

So our aim is to make S1 = S2.
The formula from the physics classes we know for a distance travelled is:
S = V / t.
So S1 = V1 / t1 and S2 = V2 / t2.
We need S1 to be equal to S2, so
V1 / t1 = V2 / t2.
We know that t1+t2 = 4 and V1 and V2's values are known.
From here onwards it is all simplification and eventually I get that the maximum time that can be travelled forward is 7/3 hours and 5/3 hours back.

As I said I cannot guarantee that the solution is correct and I am open to any critics as long as they do not leave the borders of logic and clear thinking.
• Aug 13th 2008, 12:28 AM
hungrybarts
finally i figured this out here is my working

http://img227.imageshack.us/img227/3...thgraphrb7.jpg

i suppose it has covered 1-3

now the last problem is 4