# What will be the rate of fuel consumption of a rocket near 'c'

1. May 28, 2015

### Prashan Shan

when an object moves relative to something it experiences time at a slower rate right?
now lets assume that an rocket moves 99.99% the speed of light, then what will be the rate of fuel consumption?
will it remain the same or it will increase/decrease?

2. May 28, 2015

### Mentz114

If it were moving inertially relative to something else at that speed it would consume no fuel.

You need to get clear about relative velocity. Also acceleration, which increases relative velocity and requires propulsion in the absence of gravity.

This might help with rockets

http://www.quantumg.net/rocketeq.html
[/PLAIN] [Broken]
http://www.wolframalpha.com/input/?i=Tsiolkovsky+rocket+equation

Last edited by a moderator: May 7, 2017
3. May 28, 2015

### Staff: Mentor

http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html [Broken]

Last edited by a moderator: May 7, 2017
4. May 28, 2015

### phinds

Right now you are moving at 99.9999% of c relative to a particle at CERN. How much fuel are you using?

5. May 28, 2015

### tallal hashmi

It will consume no fuel because of reltavistic effects.

6. May 28, 2015

### Staff: Mentor

It will consume no fuel if it is moving at a constant speed andnot accelerating, but this has nothing to do with any "relativistic effects". It's momma-poppa simple bone stock Newtonian mathematics: Start with $F=ma$, set $a$ equal to zero because it's moving at a constant speed, conclude that $F$ is therefore zero, and ask yourself how much fuel burn is required to produce zero force.

7. May 29, 2015

### Prashan Shan

Then what will happen if it accelerates?

8. May 29, 2015

### phinds

It will consume fuel.

9. May 29, 2015

### Staff: Mentor

To amplify on phinds' response a bit, it will consume fuel, and the amount of fuel consumed will depend on the acceleration as felt by the ship and its crew; the fact that the ship is moving at close to c relative to something else has nothing to do with it.