Rocket Velocity and Mass Ratio

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Homework Help Overview

The discussion revolves around a rocket problem involving thrust, exhaust speed, and mass ratios. Participants are exploring the implications of these factors on the rocket's velocity and mass flow rate.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to calculate the mass flow rate based on thrust and exhaust speed. There is uncertainty regarding the interpretation of the final speed question, particularly concerning the need for the original mass of the rocket.

Discussion Status

Some participants have provided calculations for the mass flow rate, while others are questioning the requirements for determining the final speed. The discussion is exploring different interpretations of the problem without reaching a consensus.

Contextual Notes

There is a mention of the rocket being 90% fuel mass, and the discussion is focused on the relationship between initial and final masses in the context of rocket velocity. Participants are navigating the constraints of the problem without explicit definitions or values for the original mass.

UrbanXrisis
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A large rocket with an exhaust speed of v=3000m/s develops a thrust of 24 million Newton.
a. How much mass is being blasted out of the rocket exhaust per second and
b. what is the max speed the rocket can attain if it starts from rest in a force-free environment with v=3000m/s and if 90% of its initial mass is fuel and oxidizer?

a. 8 thousand kg (=24mill/3000)
b. I'm not sure what the question is asking at all
 
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Another way to phrase the question would be - if the rocket is 90% fuel mass, then what is its final speed (ignoring gravity)?
 
but don't I need the original mass?
 
b) Initial and final masses only appear as a ratio in the expression for the rocket velocity.
Find the way in which that ratio appears in the velocity expression.
 
Last edited:

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