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        riddles >> easy >> An oldie: Bell tolls
        
(Message started by: otter on May 22^nd, 2003, 10:37am)

Title: An oldie: Bell tolls
Post by otter on May 22^nd, 2003, 10:37am

Think fast on this one.
If a clock takes exactly two seconds to strike two o'clock, how long does it take to strike three o'clock? 8)

Title: Re: An oldie: Bell tolls
Post by Leonid Broukhis on May 22^nd, 2003, 1:24pm

Hard to tell without knowing how long the mechanism works before the hammer hits the bell. We're given

p + i = 2 (preparation time plus interval time between the strikes)

and are asked to find

p + 2 * i

obviously, preparation time is less than or equal to i, but there is no sense to have p to be less than i: once the mechanism starts, it is easier to make it work continuously.

So, assuming p = i, the answer is 3 seconds.

The expected answer of [hide]4[/hide] seconds would have been to a problem "If it takes 2 seconds to hear a clock striking 2 o'clock, how long does it take to hear a clock striking 3 o'clock".

Title: Re: An oldie: Bell tolls
Post by otter on May 22^nd, 2003, 3:44pm

on 05/22/03 at 13:24:28, Leonid Broukhis wrote:

Hard to tell without knowing how long the mechanism works before the hammer hits the bell.

I would argue that the preparation time leading to the first strike is immaterial as a clock does not "strike" until the hammer hits the bell.

Quote:

The expected answer of [hide]4[/hide] seconds would have been to a problem "If it takes 2 seconds to hear a clock striking 2 o'clock, how long does it take to hear a clock striking 3 o'clock".

The timing begins at the first strike and ends at the moment of the last strike. If we assume the timing of the actual striking of the hammer on the bell to be instantaneous (or at least extremely small), then the pause is 2 seconds. Thus for three strikes, there are two 2-second pauses, and therefore 4 seconds elapse.

Title: Re: An oldie: Bell tolls
Post by wowbagger on May 26^th, 2003, 10:23am

As you're talking about hammers striking bells:
Where I live, the clocks in the steeples of churches strike every 15 minutes, once for every completed quarter of an hour. This makes four strikes for the quarters plus the n strikes (in a different pitch) for n o'clock. Which would lead us to a totally different result... ::)

Title: Re: An oldie: Bell tolls
Post by otter on May 26^th, 2003, 2:43pm

on 05/26/03 at 10:23:29, wowbagger wrote:

Agreed. Made even more difficult with varying chime patterns.

Title: Re: An oldie: Bell tolls
Post by mike1102 on Nov 30^th, 2004, 6:12am

It will take one hour for the clock to move from two o'clock to three o'clock - so the answer is one hour.

Title: Re: An oldie: Bell tolls
Post by Lewis Temple on Dec 9^th, 2004, 11:35pm

I think you are almost right, but it would be 1 hour and 2 seconds. remember it says it takes 2 seconds to strike 2 oclock and an hour after that would be 1 hour and 2 seconds.