Average Force on a Rocket During Gas Exhaustion

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SUMMARY

The average force exerted on a rocket during gas exhaustion can be calculated using the formula F = m(Δv) / (Δt). In this case, with a mass flow of 1150 kg of gas expelled at a velocity of -4.50×10^4 m/s over 1 second, the average force is calculated to be -5.175 x 10^7 N. The negative sign indicates direction, but the magnitude is 5.175 x 10^7 N. The discussion emphasizes the importance of understanding conservation of momentum in relation to the force exerted by the gas on the rocket.

PREREQUISITES
  • Understanding of Newton's Second Law of Motion
  • Familiarity with the concept of momentum
  • Basic knowledge of rocket propulsion principles
  • Ability to perform calculations involving mass and velocity
NEXT STEPS
  • Study the principles of conservation of momentum in rocket propulsion
  • Learn about the implications of thrust-to-weight ratio in rocket design
  • Explore advanced topics in fluid dynamics related to gas exhaust
  • Investigate the effects of varying exhaust velocities on rocket performance
USEFUL FOR

Aerospace engineers, physics students, and anyone involved in rocket design and propulsion systems will benefit from this discussion.

subopolois
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Homework Statement


Rocket engine expends 1150 kg of gas in 1 second, with a velocity of -4.50×10^4 m/s. Calculate the average force exerted on the rocket by the gas during that 1.0 second interval

Homework Equations


F= m(delat)v / (delta)t

The Attempt at a Solution


F= (1150kg)(-45000m/s) / 1 s
-5.175 x 10^7 N
 
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I would use a different sign for deltam, but apart from that it is right.
 
subopolois said:

Homework Statement


Rocket engine expends 1150 kg of gas in 1 second, with a velocity of -4.50×10^4 m/s. Calculate the average force exerted on the rocket by the gas during that 1.0 second interval

Homework Equations


F= m(delat)v / (delta)t

The Attempt at a Solution


F= (1150kg)(-45000m/s) / 1 s
-5.175 x 10^7 N
Your answer is OK except no - sign. The problem implicitly asks for a magnitude.
But, you should give a bit more detail on why that formula works, starting with conservation of momentum of the rocket/gas system:
force x 1 sec. = change per second in momentum of rocket = - change per second in momentum of the gas
etc.
 

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