Rocket thrust force calculation

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Homework Help Overview

The discussion revolves around calculating the thrust force required for a rocket with a total weight of 15,000 kg (including its payload) to achieve an acceleration of 3.5 m/s². Participants are exploring the implications of Newton's laws in this context.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants are attempting to apply Newton's second law, questioning the correct treatment of forces acting on the rocket, including thrust and weight. There are discussions about whether to add or subtract these forces and how to account for their directions.

Discussion Status

The conversation is ongoing, with various interpretations of how to calculate the resultant force and the thrust needed. Some participants are providing different perspectives on the relationship between thrust and weight, indicating a productive exploration of the problem.

Contextual Notes

There appears to be some confusion regarding the directionality of forces and the correct application of the equations involved. Participants are also navigating the constraints of the problem as a homework assignment, which may limit the information available for discussion.

robax25
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Homework Statement


A rocket has weight 10,000 kg and it needs to carry 5000 kg with acceleration 3.5 m/s². How much thrust force is necessary for the rocket to have a flight from Earth to space?

Homework Equations


F=ma[/B]

The Attempt at a Solution


I try that, According to Newton's law, ( g=10 m/s2) ΣF=ma Ft=15000 kg * 10 m/s² - 15000 kg * 3.5m/s² =97500N.
[/B]
 
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Hey may I know why did you subtract the force of rocket on Earth and force of 5 ton object accelerated at 3.5m/s2
 
Last edited by a moderator:
you will get resultant force
 
Then 3.5m/2 is the acceleration of the rocket, is that right?
 
yeah but then the equation,
F= (15000)*3.5=52500N
 
I gave it a try.. check that out..
 
why you add two acceleration? one is upward direction and another one is negative direction? My first solution is valid for space
 
robax25 said:
you will get resultant force
The resultant force is theforce that leads to its actual acceleration. The two applied forces must be added to get the resultant force.
What are the two applied forces, and what is the resultant force?
 
resultant force=thrust force- weight of the rocket, we do not add two forces and I need to subtract them because they are negative direction each other,
= 202500 N- 150000N
= 52500N
 
  • #10
robax25 said:
I need to subtract them because they are negative direction each other,
No, you add them, but one is negative: thrust + weight = 202500N + (-150000N)
robax25 said:
202500 N
Right.
 

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