Question about the upthrust of a rocket

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    Rocket Upthrust
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Homework Help Overview

The discussion revolves around calculating the thrust and resultant force of the Saturn V rocket at lift-off, using given specifications such as mass, exhaust velocity, and fuel consumption rate.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of thrust using the equation Ft = mv and question the values used for exhaust velocity and gravitational acceleration. There are attempts to clarify discrepancies in the thrust and resultant force values.

Discussion Status

Participants are actively engaging with the problem, questioning the values used in calculations, and exploring different interpretations of the problem setup. Some guidance has been offered regarding the gravitational constant, but no consensus has been reached on the correct values or calculations.

Contextual Notes

There is a noted discrepancy in the value of exhaust velocity, and participants are considering different values for gravitational acceleration as per the problem's instructions.

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Homework Statement



The Saturn V rocket which launched the Apollo space missions had the following specifications: mass at lift-off = 3.0 x 10^6 kg velocity of exhaust gases = 1.0 x 10^4 m/s initial rate of fuel consumption at lift-off = 3.0 x 10^3 kg/s 1.(a) Calculate: (i) the force (thrust) produced at lift-off (ii) the resultant force acting on the rocket at lift-off

Homework Equations



Ft = mv

The Attempt at a Solution



i got the force exerted by the exhaust gases by rearranging the equation to F = mv/t. Upthrust was 33MN. But then i have no clue how to figure the second part out, the solution page says it is 3.6MN, i keep getting 3MN, any help would be greatly appreciated!
 
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I don't see how you got the thrust value of 33 MN from the given information, notr how they arrived at 3.6 MN for the resultant force. Check the given value for the exhaust velocity: Was it perhaps a bit higher than 1.0 x 104 m/s?
 
My bad, it's 1.1*10^4 m/s
 
ThatOneMidget said:
My bad, it's 1.1*10^4 m/s
Does that resolve your issues?
 
I'm still getting 3MN for the net force, and 33MN for the upthrust
 
It seems like the book used 9.81 as a value for g although it stated to use 10 = g, anyways I've got it :D
 
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