Re: SQL Fun Challenge #3

Daniel Morgan wrote:

> Gave this one to my students tonight.
>
> There are two solutions ... one easy and one that requires coding
> a function. Can you find them both?
>
> "Train 1" leaves station A heading east at 10:00am, "Train 2" leaves
> station B heading west at the same time. The two trains are moving
> towards each other on the same track and are 114 miles apart.
>
> The trains move at a constant 50 miles per hour. There is a bird perched
> on "Train 1". The bird begins to fly east as soon as "Train 1" begins
> to move. The bird flys at a constant 20 miles per hour and flies back
> and forth between "Train 1" and "Train 2" as the trains approach each
> other. The bird has perfect recoil (it spends 0 time perched on either
> train and experiences no acceleration and no deceleration). How many
> miles does the bird fly before the trains collide?
>
> And since my students got this first: Yes the bird is dimensionless.
>

Naive answer:

As the bird (constant 20mph) flies slower than the trains (constant 50mph) it won't fly back and forth at all, instead it will lag behind "Train 1". It will fly one-way until the trains collide, at 2/5th the trains speed. The trains collide after 114/2 miles, so the bird flies (114 miles *2)/(2*5) = 114/5 = 22.8 miles in the same time span.

Or did I misunderstand the setup? It appears to me that to make sense the question requires that the bird flies faster than the trains.

Yours,
Stephan Received on Fri Mar 12 2004 - 04:36:17 CST