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HSC Physics Question Thread
jakesilove:
--- Quote from: Happy Physics Land on February 05, 2016, 07:01:25 pm ---Oh crap I totally forgot that I still had the job to derive this for you sire 123!! Im so sorry and thank you so much Jamon for remembering to derive the two formulae for sire 123!!! You are such a legend!
But yeah I dont feel like I have done my job properly so l will take the rocket propulsion proof a step further, way back to the first principles so that you can see how rocket propulsion is related to the Law of Conversation of Momentum, keeping in mind that when a rocket launches, the force with which gas acts on the rocket (F_{gr} = Force of gas on rocket) is equal to the force with which the rocket acts onto the gas (F_{rg} = Force of rocket on the gas).
(Image removed from quote.)
So yeah anyways sorry sire for such a late reply, hope this will help you to understand how the law of conservation of momentum is involved with rocket launch, great question! :)
Best Regards
Happy Physics Land
--- End quote ---
Absolute legend, also can't pass up a good derivation so I'm so sad I missed out on this/
Jake
Happy Physics Land:
--- Quote from: jakesilove on February 05, 2016, 09:06:43 pm ---Absolute legend, also can't pass up a good derivation so I'm so sad I missed out on this/
Jake
--- End quote ---
Don't worry Jake, God has got bigger derivation plans for you ahead
AladinX:
Hey Jake.
I'm currently a Year 12 student in Physics and am soon going to be given an assessment task requiring me to make a rocket launcher ( testing our knowledge of projectile motion ). Any ideas on where to start for such an assignment. What to use maybe to launch the rocket to the required distance?
Much appreciated, thanks.
jakesilove:
--- Quote from: AladinX on February 05, 2016, 11:49:08 pm ---Hey Jake.
I'm currently a Year 12 student in Physics and am soon going to be given an assessment task requiring me to make a rocket launcher ( testing our knowledge of projectile motion ). Any ideas on where to start for such an assignment. What to use maybe to launch the rocket to the required distance?
Much appreciated, thanks.
--- End quote ---
Hey AladinX!
Firstly, that's a seriously cool assignment! Tricky, but cool. I'm sure heaps of people on the forum will have great ideas, so hopefully everyone can contribute!
Secondly, I think we need a little more information about the project. Is the rocket launcher supposed to be accurate, or just launch a projectile further than a required distance? Is there a target? What is the required distance? How heavy is the projectile?
If you just need to launch a projectile greater than a required distance, and accuracy doesn't matter, I'd build yourself a good ol' fashion Potato Gun. Google the method, but it's cheap to make and works like a charm. You could vary the construction depending on how far you want it to go etc.
If you need accuracy, typically people build trebuchets and other similar launchers. Again, I can go more in depth when I have the answers to the above questions, but I'm thinking that building something like that would be really difficult. What I'm imagining is sort of "cheating" the question: if all that is required is launching a projectile a set distance, accurately, I would buy something like Hot Wheels tracks, set up a ramp and fling is to the point you need to get to. You can easily do the calculations, doesn't required difficult construction etc. etc.
Let me know more information! Hopefully other people on the forum have more ideas, because whilst I love theoretical Physics I am certainly not an Engineer.
Jake
Happy Physics Land:
--- Quote from: AladinX on February 05, 2016, 11:49:08 pm ---Hey Jake.
I'm currently a Year 12 student in Physics and am soon going to be given an assessment task requiring me to make a rocket launcher ( testing our knowledge of projectile motion ). Any ideas on where to start for such an assignment. What to use maybe to launch the rocket to the required distance?
Much appreciated, thanks.
--- End quote ---
Hey AladinX:
I havent had any experience with constructing a rocket model to test projectile motions, however I have found two very useful sites that outlines two different types of rocket launchers that you may be able to use to demonstrate your knowledge of projectile motion. You can use the IDEA from these two websites (not the same methods or results or safety of course) and twist them and changed them to avoid being accused of plagiarism. So yeah you can have a read of these two sample experiments to inspire some ideas for yourself!
http://www.scienceworld.ca/resources/activities/pop-bottle-rocket-part-ii-projectile-motion
http://www.arborsci.com/cool/projectile-motion-for-everyone
Best Regards
Happy Physics Land
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