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        riddles >> easy >> street racing record
        
(Message started by: lukes new shoes on Dec 4^th, 2002, 11:44pm)

Title: street racing record
Post by lukes new shoes on Dec 4^th, 2002, 11:44pm

one day u deciede ur going to try and beat the fastest time for driving from one side of ur town to the other.

u bring two witnesses along so they can record ur time for u. they try following u to record ur time but they cant keep up!

the witnesses cant ride in the car with u because the extra weight will slow u down.
ur not allowed to time urself because u mite cheat.
how do u record ur time?

Title: Re: NEW: street racing record
Post by TimMann on Dec 5^th, 2002, 11:10am

Have the witnesses synchronize their watches and drop one off on each side of town before you start. Or have them communicate by cell phone so that they don't have to synchronize their watches. What's hard about that?

Title: Re: NEW: street racing record
Post by lukes new shoes on Dec 5^th, 2002, 6:02pm

its not ment to be hard, thats why its under EASY.
p.s. the witnesses dont have watches or cell phones. they only bought along their stop watches so they they could make an exact reading.

Title: Re: NEW: street racing record
Post by Pietro K.C. on Dec 5^th, 2002, 6:53pm

Assuming everything to be perfect, you could theoretically go across town and come back in exactly double the time of just going. So, just drop a witness off at one end of town and go to the other end with the other witness. Have the witness you brought along start his/her stopwatch as you drive off, and stop it as soon as you come back. Your new record is half the time he/she finds on the watch. The witness on the other side of town just serves to make sure you actually went there.

Or, you could start both watches at the same time, like Tim said, and take one of the witnesses to the other side of town. Then, start driving. The first witness will be able to tell the other when you left, so it is enough to subtract the two times.

Title: Re: NEW: street racing record
Post by Jonathan_the_Red on Dec 9^th, 2002, 9:09am

on 12/05/02 at 18:53:20, Pietro K.C. wrote:

A slightly better solution along these lines is this:

Both witnesses zero their stopwatches.
You start your run. Witness A starts his watch when you cross the starting line.
Witness B starts his watch when you cross the finish line.
You turn around and get lined up for your second run. As soon as you cross the finish line (now the starting line), Witness B stops his watch.
Witness A stops his watch when you cross the starting line (now the finish line).

Your average time per run is (A-B)/2.

Title: Re: NEW: street racing record
Post by James Fingas on Dec 9^th, 2002, 9:28am

Great work Pietro!

Here's an even better version, inspired by Pietro's:

1) A and B start out at the start and finish lines respectively.

2) A starts his watch when you cross the start line.

3) B starts his watch when you cross the finish line.

4) Drive (at normal speed) back to the start line with B in your car.

5) A and B get together and stop their watches at the same time. Your elapsed time is A-B.