How long until the water reaches the top step on this 5th grade brain teaser?

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SUMMARY

The discussion centers on a brain teaser involving a boat, a ladder, and rising tide levels. The ladder has four steps, each 20 cm apart, and the tide rises at a rate of 5 cm per minute. Participants conclude that the water will never reach the top step of the ladder because the boat rises with the tide, maintaining the same distance from the water level. The mathematical interpretation suggests that the problem involves differential equations, but the consensus is that the answer is straightforward: the water will not reach the top step.

PREREQUISITES
  • Understanding of basic physics principles related to buoyancy and floating objects.
  • Familiarity with differential equations and their applications.
  • Knowledge of tide dynamics and their effects on floating structures.
  • Basic problem-solving skills suitable for 5th-grade level mathematics.
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  • Study the principles of buoyancy and how they apply to floating objects.
  • Learn about differential equations and their relevance in real-world scenarios.
  • Research the effects of tidal movements on boats and other floating structures.
  • Explore problem-solving techniques for mathematical brain teasers and puzzles.
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This discussion is beneficial for educators, students tackling physics and mathematics problems, and anyone interested in understanding the dynamics of floating objects in relation to rising water levels.

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A boat is docked at a shore. A ladder is hanged from top of the boat So that the last step is touching the water. The distance between steps is 20 cm and there are 4 steps in the ladder. A tide is raising the water-level 5 cm a min. How long will it take for the water to reach the top step.
 
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Phew ! :confused: That's a real toughie ! Luckily, I'm not in the 5th grade. :wink: :biggrin:

Otherwise, I may have complained about insufficient information ! :rolleyes:
 
16 minutes
 
gabe said:
16 minutes

I guess you're not in the 5th grade either, eh ?
 
I'd say a 5th grader was trying to get his homework question answered. Hmm, smart enough to trick you but not smart enough to do the problem.

Ohh, and it is only 12 minutes.
 
Last edited:
ExtravagantDreams said:
I'd say a 5th grader was trying to get his homework question answered. Hmm, smart enough to trick you but not smart enough to do the problem.

Ohh, and it is only 12 minutes.

That would be the correct wrong-answer !
 
Last edited:
how is the boat docked? if it is far up on shore, not floating, and the tide level won't affect its position then i'd agree with the 12 minutes. however, if the boat is docked such that it is floating, then the tide won't move relative to the ladder.
 
its a differential equation!

i donno :D
 
The answer seems obvious to me. No math needed. But then I live down the street from a Marina.

(am I missing something?)
 
  • #10
Gokul43201 said:
That would be the correct wrong-answer !

Man I hate those
 
  • #11
Math Is Hard said:
The answer seems obvious to me. No math needed. But then I live down the street from a Marina.

(am I missing something?)

(No, you're not.)
 
  • #12
it will never reach the top step as the boat also rises with the tide.
 
  • #13
vikasj007 said:
it will never reach the top step as the boat also rises with the tide.

indeed. :smile:
 
  • #14
notice these two geeks used relativity for a 5th grade problem :-p


i still think there's a differential equation..
 
  • #15
cronxeh said:
notice these two geeks used relativity for a 5th grade problem :-p


i still think there's a differential equation..

Yes there is :

dx/dt = 5 = dy/dt

x(t=0) = 0

y(t=0) = 60

find t when x=y.
 
  • #16
hahaha funny
the boat will just rise so the water never rises up the ladder all the way-- unless the boat sinks
 
  • #17
well i am in 5th grade so probably wrong, but wouldn't the ladder rise with the boat
just a guess:biggrin:
 
  • #18
Tom McCurdy said:
hahaha funny
the boat will just rise so the water never rises up the ladder all the way-- unless the boat sinks

:smile: :smile: :smile:
 

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