Why can a rocket coast to the moon without its engine running?

  • Context: High School 
  • Thread starter Thread starter 1234
  • Start date Start date
  • Tags Tags
    Engine Moon Rocket
Click For Summary

Discussion Overview

The discussion revolves around the question of why a rocket can coast to the moon without its engine running. Participants explore the principles of motion in space, particularly focusing on the absence of friction and air resistance, as well as the implications of Newton's laws of motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the lack of friction and air resistance in space allows a rocket to maintain its speed after gaining momentum from its engines.
  • One participant describes the conservation of momentum as a fundamental principle, noting that without external forces, a body's motion remains unchanged.
  • Another participant mentions that while keeping engines on could theoretically shorten travel time, the inefficiency of chemical rockets would require an impractical amount of fuel.
  • Newton's First Law is referenced, indicating that a body will maintain its state of motion unless acted upon by an external force, which aligns with the earlier points about the conditions in space.
  • There is a clarification that no external force results in no acceleration, leading to no change in speed, which supports the idea of coasting to the moon.

Areas of Agreement / Disagreement

Participants generally agree on the principle that the absence of external forces allows a rocket to coast, but there are varying interpretations and additional considerations regarding the implications of this principle.

Contextual Notes

Some assumptions about the efficiency of rocket fuel and the nature of motion in space are present, but these are not fully explored or resolved within the discussion.

1234
Messages
4
Reaction score
0
Why can a rocket travel to the moon with it's engine off?

i know that it's because space has no friction, air resistance so the rocket can travel when it's gained speed from traveling out of the atmosphere.
but are there any other reasons to that?
 
Physics news on Phys.org
Well, I think we can tell it as "the art of the nature".
Nature acts in a way that if no external force act on the body, its momentum is conserved.
It is the fact of the nature that we have detected it.
And we don't know why!
(Or maybe WE know and 'I' don't know!)
 
1234 said:
Why can a rocket travel to the moon with it's engine off?

i know that it's because space has no friction, air resistance so the rocket can travel when it's gained speed from traveling out of the atmosphere.
but are there any other reasons to that?

If you could leave your engines on you might get there and back a lot quicker! However, the fuel requirements would be enormous as chemical rockets are depressingly inefficient and you would need a LOT of fuel just to transport the fuel itself.
 
1234 said:
Why can a rocket travel to the moon with it's engine off?

i know that it's because space has no friction, air resistance so the rocket can travel when it's gained speed from traveling out of the atmosphere.
but are there any other reasons to that?

It's Newton's First Law in action - a body maintains its state of motion unless acted on by an outside force. Since, as you pointed out there is essentially no friction or air resistance in space, there is no force to change the rocket's state of motion.
 
ohhh
the only reason is because no external force ?
 
No force means no acceleration. No acceleration means no change in speed. No change in speed means you can coast to the moon (well, very little change in speed in that case). QED
 

Similar threads

  • · Replies 26 ·
Replies
26
Views
4K
  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 13 ·
Replies
13
Views
10K
  • · Replies 120 ·
5
Replies
120
Views
20K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 19 ·
Replies
19
Views
4K