# Rocket thrust force calculation

## 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]

Sudarsan
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

Sudarsan
Then 3.5m/2 is the acceleration of the rocket, is that right?

yeah but then the equation,
F= (15000)*3.5=52500N

Sudarsan
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

haruspex
Homework Helper
Gold Member
2020 Award
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

haruspex