# Rocket thrust force calculation

• robax25
In summary, the question asks for the necessary thrust force for a rocket with a weight of 10,000 kg and a payload of 5000 kg, to have a flight from Earth to space with an acceleration of 3.5 m/s². Using Newton's second law, the resultant force is calculated by adding the thrust force and the weight of the rocket, with one force being in the negative direction. The final answer is 52500N.
robax25

## 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?

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]

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

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.

## What is rocket thrust force calculation?

Rocket thrust force calculation is the process of determining the amount of force a rocket engine generates as it expels exhaust gases in order to propel the rocket forward. This force is a crucial factor in designing rockets and predicting their performance.

## How is rocket thrust force calculated?

Rocket thrust force is typically calculated by multiplying the rate of mass flow from the rocket engine by the velocity of the exhaust gases as they exit the nozzle. This calculation can be further refined by taking into account factors such as atmospheric pressure and temperature, as well as the specific impulse of the engine.

## What is specific impulse and how does it affect rocket thrust force?

Specific impulse is a measure of the efficiency of a rocket engine and is defined as the thrust force produced per unit of propellant consumed. A higher specific impulse means a more efficient engine, which can result in a greater thrust force.

## What are some challenges in accurately calculating rocket thrust force?

There are several challenges in accurately calculating rocket thrust force, including variations in atmospheric conditions, irregularities in engine performance, and complex interactions between the rocket and its environment. Additionally, precise measurements of mass flow rate and exhaust velocity can be difficult to obtain.

## How is rocket thrust force used in rocket design and engineering?

Rocket thrust force is a critical factor in designing and engineering rockets. It helps determine the size and shape of the rocket, as well as the amount of propellant needed for a successful launch. Additionally, accurate calculations of thrust force can aid in predicting the trajectory and performance of the rocket.

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