Minimum Rate of Rocket Fuel Consumption

[nx01]

Homework Statement

A rocket which has an exhaust speed of 8.0 km/s is to have a vertical acceleration of 8.0 m/s². If the initial mass of the rocket is 6.0x10⁶ kg, at what minimum rate must the rocket consume fuel?

Homework Equations

F = ma
F = RV_REL

The Attempt at a Solution

F = (6.0x10⁶ kg)(8.0 m/s²) = 4.8x10⁷ N

R = (4.8x10⁷ N) / (8000 m/s) = 6000 kg/s.


The back of the book tells me this answer is wrong. I would appreciate any insight into the error(s) I am making.

Thank you!

 

[SteamKing]

I think you must apply Newton's Second Law to the rocket as it lifts off. Your F value is F(net) and not the actual thrust produced by the rocket motor.

 

[nx01]

Thanks!