Momentum Changes in a variable mass system.

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The discussion focuses on preparing a presentation about momentum changes in variable mass systems, specifically in the context of rocket propulsion. The equation m(t)a=Rv is highlighted, where R represents the mass loss rate and v is the ejected gas velocity. The user seeks realistic examples and clarification on how to apply the equation, expressing uncertainty about the necessary variables. Suggestions include using resources from Michael Richmond at RIT and considering simpler examples like cars to avoid complications from gravity and air resistance. The overall goal is to create accessible problems for an audience with limited physics background.
Faustian
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Pleeeease help me. I have to do a twenty minute presentation on momentum changes in variable mass systems. I have everything done but examples. The equation I have is m(t)a=Rv where R is the rate the mass of the rocket is decreasing and v is the velocity of the gas ejected with respect to the rocket. Does anyone have any examples from the internet I can use? At least any realistic variables? I have absolutely NO idea what realistic numbers would be for this situation. Actually, to be honest, I'm not really sure how to use the equation. What would I have to have to solve for a sample? The velocity of the particles ejected, the time and rate of change of the mass? Then I would just use the rate of change and the time to find m(t) and I would solve for a? :frown: This is actually for AP Calculus, but I'm pretty sure this concept is a bit advanced for the high school level (My physics teacher couldn't even help me, which is kind of sad). Please, any help will really be appreciated.
 
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Umm… ok. Well, that certainly sounds like an interesting presentation but a lot of work. I hope you're enjoying it.
There is a site by Michael Richmond, Dept. of Physics Rochester Institute of Technology, which should be helpful.
http://spiff.rit.edu/classes/phys311_t/workshops/w10a/rockets/rockets.html
It lists two rockets and the fuel used in there deployment. You might have already considered this, but using cars as examples might be simpler, as you don’t have to consider changes in gravity and air density.
 
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Thank you. That looks like it'll help. The thing is, most of the people in my calculus class haven't even taken a basic physics class. Because of this, I can make my problems as simple as possible. The samples I use won't even have ANY gravity or air resistance.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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