Minimum Rate of Rocket Fuel Consumption

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SUMMARY

The minimum rate of fuel consumption for a rocket with an exhaust speed of 8.0 km/s and an initial mass of 6.0x106 kg, required to achieve a vertical acceleration of 8.0 m/s2, is calculated using Newton's Second Law. The thrust force is determined to be 4.8x107 N. The correct fuel consumption rate is found to be 6000 kg/s, but this value is identified as incorrect due to the misunderstanding that the force calculated is the net force rather than the actual thrust produced by the rocket motor.

PREREQUISITES
  • Understanding of Newton's Second Law (F = ma)
  • Knowledge of thrust calculation in rocketry (F = RVREL)
  • Familiarity with exhaust speed and its impact on fuel consumption
  • Basic principles of rocket dynamics and mass flow rate
NEXT STEPS
  • Review the principles of thrust and net force in rocketry
  • Study the concept of mass flow rate in propulsion systems
  • Learn about the Tsiolkovsky rocket equation and its applications
  • Explore advanced topics in rocket propulsion and fuel efficiency
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Aerospace engineers, physics students, and anyone involved in rocket design and propulsion systems will benefit from this discussion.

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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 = RVREL

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!
 
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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.
 
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Thanks!
 

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