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Topic: An oldie: Bell tolls (Read 1182 times) |
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otter
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An oldie: Bell tolls
« on: May 22nd, 2003, 10:37am » |
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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? 
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We shall not cease from exploration. And the end of all our exploring will be to arrive where we started
and know the place for the first time.
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Leo Broukhis
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Re: An oldie: Bell tolls
« Reply #1 on: May 22nd, 2003, 1:24pm » |
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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 4 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".
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otter
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Re: An oldie: Bell tolls
« Reply #2 on: May 22nd, 2003, 3:44pm » |
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on May 22nd, 2003, 1:24pm, Leonid Broukhis wrote:| Hard to tell without knowing how long the mechanism works before the hammer hits the bell. |
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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 4 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". |
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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.
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We shall not cease from exploration. And the end of all our exploring will be to arrive where we started
and know the place for the first time.
T.S. Eliot
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wowbagger
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Re: An oldie: Bell tolls
« Reply #3 on: May 26th, 2003, 10:23am » |
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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... 
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otter
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Re: An oldie: Bell tolls
« Reply #4 on: May 26th, 2003, 2:43pm » |
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on May 26th, 2003, 10:23am, wowbagger wrote: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... |
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Agreed. Made even more difficult with varying chime patterns.
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We shall not cease from exploration. And the end of all our exploring will be to arrive where we started
and know the place for the first time.
T.S. Eliot
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mike1102
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It will take one hour for the clock to move from two o'clock to three o'clock - so the answer is one hour.
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Lewis Temple
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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.
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