Design a mechanism which knocks over can

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Discussion Overview

The discussion revolves around designing a mechanism that can be placed inside a closed can to knock it over after a 6-second delay. Participants explore various ideas, constraints, and materials for this project, which appears to be related to a homework assignment.

Discussion Character

  • Homework-related
  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant asks about limitations on materials and technology, indicating uncertainty about the project requirements.
  • Another participant suggests using a small firecracker or a balloon with a candle as potential mechanisms, but later acknowledges the need to avoid fire.
  • A participant proposes using a balloon that bursts to create a sideways air jet, contingent on developing a timer mechanism to pop the balloon after 6 seconds.
  • Concerns are raised about the closed nature of the can, leading to discussions about using a moving mass or rotation to achieve the desired effect.
  • Some participants emphasize the importance of creativity and personal effort in developing a unique design, while others express frustration about the limitations imposed by previous ideas being taken.
  • A participant mentions the possibility of making holes in the can for triggering mechanisms, which could influence design options.
  • There is a suggestion to consider energy storage for a rotating mass and potential non-fire-based timing methods.

Areas of Agreement / Disagreement

Participants express a mix of ideas and constraints, with no clear consensus on a specific design approach. Some participants are frustrated by the limitations of their ideas being previously used, while others encourage creativity and exploration of new concepts.

Contextual Notes

Participants mention the need for a closed can and the requirement for a 6-second delay, which may limit design options. The discussion includes various proposed mechanisms, but no definitive solutions are reached.

Who May Find This Useful

Students or individuals interested in mechanical design, project development, or those facing similar homework challenges in engineering or physics.

key
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I really need help fast. I need to design a mechanism which has to be placed inside a can. The purpose of the mechanism is to knock the can over. I also have to have a 6 seconds delay before the can is to tip.
I can use any kind of can
thank you
 
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What are your initial thoughts? Is the only limitation that the mechanism fit in side the can? Any other limits on materials or technology? Are you actually going to build it, or just write up the plans?
 
Programmable electric shock collar for a gerbil?

This sounds like homework. Do you have any ideas already key?
 
no see the ideas i had were the same as others and only one person can use an idea
there are no limits on technology
 
Okay, I have a good one, but I'm not sure they will allow it. Can you use a small firecracker? If not, maybe a balloon and a candle...
 
berkeman said:
Okay, I have a good one, but I'm not sure they will allow it. Can you use a small firecracker? If not, maybe a balloon and a candle...

No, a balloon and a 6 second fuse...that would work, and be reasonably safe.
 
i am sorry but is there anything that does not involve fire

Also how would i set up the fuse and balloon
 
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key said:
i am sorry but is there anything that does not involve a fuse or fire

Sure. You're not allowed any fire, eh? Probably a smart move by the instructor.

Okay, you can still use the balloon idea (Quiz Question -- what do you need to do inside the open-top can to turn the bursting balloon into a sideways directed air jet?). You just need to come up with a 6-second timer mechanism that pops the balloon when it expires. I can think of a couple ways of doing it, but will leave that for you to do. Tell us what you come up with.
 
i am sorry but i really don't know please please help and the can top has to be closed
 
  • #10
key said:
i am sorry but i really don't know please please help and the can top has to be closed

Well you didn't say that before. Please be precise -- we could have both saved a lot of time.

So you need a moving mass inside, right? With a closed can, there would seem to be no other option. Translation and rotation would seem to be two options. Tell us how you could use rotation... And tell us some of your ideas for how to time the 6 seconds. BTW, how are you supposed to initiate the start of this 6 second timer if the can is sealed up?
 
  • #11
sorry you can make holes inside the can or the lid for the trigger
 
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  • #12
berkeman said:
(Quiz Question -- what do you need to do inside the open-top can to turn the bursting balloon into a sideways directed air jet?).

That's a mean question! If you think about conservation of momentum, some of the "obvious" answers probably won't work.

Anyway, who said the can has to have an open top? Is there any rule that says you can't turn the can upside down and have an open base (i.e. start your device, put the can over it, and wait for 6 seconds...)

(Edit: I posted that before I saw your post about "the can has to be closed")
 
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  • #13
the can has to be upward you can not turn upside down
 
  • #14
key said:
sorry you can make holes inside the can or the lid for the trigger

Well, there you go then. Rotating mass with an energy source, and a timer mechanism for the trigger. Sketch it up, get it approved, and start building!
 
  • #15
sorry but I still don't know what to do
 
  • #16
key said:
sorry but I still don't know what to do

You are not trying very hard. We do not give out answers here on the PF to homework and coursework questions. Those questions are normally supposed to go in the Homework Help forums, and you are required to show your work and efforts in order for us to be able to help you. Please review the PF rules if you haven't seen them already:

https://www.physicsforums.com/showthread.php?t=5374

I've allowed this question to stay here in the general technical forums, because questions about projects are allowed in the technical forums, although that is usually reserved for more advanced upper division projects.

Now, we are not going to give you a design here. That is your job as a student to use what you are learning in the class, plus use some of your creativity, to come up with ideas and pick the best one and build and test it. We can give you some global ideas and things to think about, but we will NOT hand you a design.

Now look at what I've posted as my latest hints, and start sketching. What is a simple way to store energy for a rotating mass? What would be some potential ways to time 6 seconds (without any fire as you say)? How could you make a mechanism to trigger the release of the stored energy as the timer expires?
 
  • #17
sorry but i am trying hard and like i said before all my ideas have been taken in my class so i can not use them
 
  • #18
key said:
sorry but i am trying hard and like i said before all my ideas have been taken in my class so i can not use them

Please go ahead and post a list for us of your ideas so far that are taken.
 
  • #19
i figured it out thanks
 
  • #20
key said:
i figured it out thanks

Figured out how to build your project, or figured out how the PF works? :rolleyes:
 

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