How Do You Calculate the Thrust of a Rocket at Takeoff?

[kmax12]

Calculate the force exerted on a rocket, given that the propelling gases are expelled at a rate of 1200 kg/s with a speed of 39700 m/s (at the moment of takeoff).

DO i just multiply? do i have to take gravity into consideration?

 

[MrXow]

Use conservation of energy along with Newton's third law.

 

[kmax12]

so i muliply 1200 and 39700 to get the reaction force , that equals 47,640,000. Is that my answer