Measuring time with burning wick

  • Thread starter Deleted member 4993
  • Start date
D

Deleted member 4993

Guest
I have two wicks - each 3 ft. long.

Each takes exactly 1 hr to burn - end to end. However, they do not burn uniformly - that is there is no guarantee that 1/6 of the wick will burn in 10 minutes. Also - once lit the wicks will not go out till the fuel is finished.

With those two wicks and a lighter - how can you measure exactly 45 minutes.

[hint: how can you measure exactly 1/2 hr]
 
I have two wicks - each 3 ft. long.

Each takes exactly 1 hr to burn - end to end. However, they do not burn uniformly - that is there is no guarantee that 1/6 of the wick will burn in 10 minutes. Also - once lit the wicks will not go out till the fuel is finished.

With those two wicks and a lighter, how can you measure 45 minutes

Consider a wick of length A with a totally varying burn rate that completely burns out in one hour when lit at either end. If lit at one end, the charring will reach a specific point along the length after 30 minutes. From this point on, there remains 30 minutes of additional burning time. If lit at the other end, the same point will be reached in 30 minutes. By definition therefore, if lit at both ends, the burning will reach this same point simultaneously in 30 minutes.

The same holds true for the other wick.

Simultaneously light both ends of wick A and one end of wick B. In 30 minutes, when wick A burns out, wick B will still have 30 minutes of burning time left.

Light the other end of wick B, which by the principal described above, will now burn out in 15 minutes.

Result: 30 + 15 = 45
 
You must log in or register to reply here.
Top