What is the correct maximum altitude and flight time calculation for a rocket?

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Homework Help Overview

The problem involves calculating the maximum altitude and flight time of a rocket that accelerates vertically. The rocket has a specified mass, fuel weight, and acceleration, with a focus on the effects of fuel consumption and neglecting air resistance.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculations for maximum altitude and flight time, with one participant questioning the validity of a provided formula. There is also a discrepancy in the calculated flight time between participants.

Discussion Status

The discussion includes attempts to clarify calculations and resolve differences in flight time estimates. Some participants express gratitude for assistance, indicating a collaborative effort to understand the problem better.

Contextual Notes

There is mention of an incorrect formula being used in calculations, and a request to ignore a specific answer provided in an image, suggesting that assumptions or interpretations may be under scrutiny.

Coffeepower
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Homework Statement


A 200kg rocket is loaded with 100kg of fuel and fired straight up. It accelerates at 30m/s^2 for 30sec and then runs out of fuel. Ignore any air resistance effects.

a. What is the maximum altitude of the rocket?
b. How long is the rocket in te air?
c. Draw a position vs. time graph of the rocket from launch to impact.

The Attempt at a Solution



http://www.angelfire.com/planet/garciarussellchem/coolpix/

The text says that the answer to (b) is 228sec. I say it is 181.69sec. what happened here?

p.s. Ignore the circled answer for (b) in the figure because it is wrong.
 
Last edited:
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Show how you arrived at your answer. (The image is blank.)
 
http://www.angelfire.com/planet/garciarussellchem/coolpix/

Just updated the image. Try it now.
 
In part of your calculation you use this formula, which is incorrect:
[tex]v_f = v_i + 2a\Delta t[/tex]
 
Thank you. That really helped out.

I got 227.6 = (rounded) 228sec.
 

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