Difficult Logic Question

[city_slick]

Hi,

I was given this problem by my teacher and am curious to know how many science enthusiasts of you can solve it.

It took me quite a while. Take a look:

 

There are two lengths of rope.

Each one can burn in exactly one hour.

They are not necessarily of the same length or width as each other.

They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.

By burning the ropes, how do you measure exactly 45 minutes worth of time?

 

You can see the answer here:

http://mindcipher.com/puzzle/41-burning-rope

 

Enjoy!

[jian]

First burning one of the rope, say A, on both sides and one side of the other rope B at the same time. When A is wipes out, burn the other side of B until B finally disappears.

From the begining to B burns out, 45mins is obtained.

[ChemSiddiqui]

fair enough, although i couldnt quite understand the explaination,,, i get to scared from long explainations.

[johnbrandy]

I am curious as to whether the rate of combustion would be effected, with respect to which end of either rope was ignited first. Depending on the characteristics of the rope, this possibility might render less exact the predicted results of the above, otherwise excellent and plausible explanation.

[CaptainPanic]

If you have a rope, with varying thickness, then I'd find it a nightmare to cut a piece that burns for exactly 1 hr.

 

The real challenge is not to solve this logic question, but to do it in reality