At What Time Do Hour and Minute Needles Coincide After 12'O Clock?

  • Context: High School 
  • Thread starter Thread starter sheperd
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Discussion Overview

The discussion revolves around determining the exact time after 12:00 when the hour and minute hands of a clock coincide again. Participants explore mathematical reasoning and various approaches to this problem.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant asks for the time after 12:00 when the hour and minute hands coincide.
  • Another participant suggests that the time is 1:05.
  • A participant provides a detailed breakdown of the movements of the hour and minute hands, calculating angles and suggesting that the first coincidence occurs at approximately 1:05:27.2727...
  • There is a challenge to consider the coincidence of the hour, minute, and second hands together.
  • One participant asserts that 12:00 is the only answer, prompting a request for proof of this claim.

Areas of Agreement / Disagreement

Participants express differing views on the time of coincidence, with some proposing specific times and others challenging those claims. The discussion remains unresolved regarding the exact time after 12:00 when the hands coincide.

Contextual Notes

Participants rely on different assumptions about the movements of the clock hands and the definitions of coincidence, which may affect their conclusions.

sheperd
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Hi

I just want to know in a clock, 12’O clock both needles (hour and minute) will coincide (one over the other)
My question is exactly at what time both needles will coincide again after 12’o clock

Good luck.
 
Mathematics news on Phys.org
13.05 :shy: ?
 
movement of hourhand:
hour hand moves 360 degree in 12 hours.
one hour is 30 degree. or 60 minutes =30 degree movement
6 minutes = 3 degrees
one minute= .5 degrees.
5 minutes =2.5 degrees

minute hand moves 360 degrees in 60 minutes
5 minutes = 30 degrees
one minute =6 degrees
at 1:05 the hour hand is at 32.5 degrees . minute hand is at 30 degrees
 
Let [itex]\theta_h[/itex] be the angle of the hour hand away from the 12, and [itex]\theta_m[/itex] be the angle of the minute hand away from the 12. Then I think you can see that
[tex]12\,\theta_h=\theta_m+360^\circ n[/tex]
where n is an integer. Now set [itex]\theta_m=\theta_h[/itex] and solve for each n. For example, the first coincidence is at [itex]\theta_{h,m}=360^\circ/11[/itex], or 1:05:27.2727...
 
Yes, but can you do it with hour, minute and second hands all coinciding? :-)
 
12:00
this is the only answer...
 
Can you prove it? :-)
 

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