What is G-Force Before Engines Turn On?

[DocZaius]

I was looking at this graph and wondering what the value of the graph would be before the engines turn on. Should it be 1 g-force or 0 g-force? (the "force" in g-force being a misnomer as it is a measure of acceleration, not force) Below are arguments for each:

Why it should be 1 g-force: We experience 1 g-force of acceleration on Earth's surface. The astronauts would also experience 1 g-force before the engines turn on.

Why it should be 0 g-force: The acceleration of the rocket (in m/s^2) is clearly 0 while the rocket is still on the ground. 0 m/s^2 corresponds to 0 g-force.

Which is the correct interpretation? Or is this just a problem of choosing your zero? In that case what is the convention?

 

[A.T.]

Why it should be 1 g-force: We experience 1 g-force of acceleration on Earth's surface. The astronauts would also experience 1 g-force before the engines turn on.

That's "proper acceleration":
http://en.wikipedia.org/wiki/Proper_acceleration

Why it should be 0 g-force: The acceleration of the rocket (in m/s^2) is clearly 0 while the rocket is still on the ground. 0 m/s^2 corresponds to 0 g-force..

That's "coordiante acceleration" in the rest frame of the surface:
http://en.wikipedia.org/wiki/Acceleration

Which is the correct interpretation?

If it says "G-force" it probably means proper acceleration. Also because it drops to 0 during stage changes. Coordinate acceleration would drop to -1g.

 

[DocZaius]

Ah I should have paid attention to the stage changes! No ambiguity there. Thank you!

 

[A.T.]

Ah I should have paid attention to the stage changes!

And also the figure caption:

8. With the cut-off of the S-IVB's first burn, the vehicle is in orbit with zero acceleration.

 

[PJC01]

I can provide a response to the question of what is G-Force before engines turn on. G-Force, or gravitational force, is a measure of the acceleration that an object experiences due to gravity. This can also be referred to as "g-loading" or "g-forces". Before the engines turn on, the rocket is still on the ground and not accelerating, so the acceleration due to gravity is 0 m/s^2. This means that the g-force would also be 0.

However, it is important to note that the term "g-force" is often used in a more general sense to refer to any type of acceleration, not just that due to gravity. In this case, the value of the graph before the engines turn on could be interpreted as 1 g-force, as the rocket is still experiencing the Earth's gravity at a constant rate of 1 g.

It is also important to consider the convention used in the graph. If the graph is measuring the acceleration of the rocket in terms of g-forces, then the value before the engines turn on would be 0 g-force. However, if the graph is measuring the acceleration in terms of m/s^2, then the value before the engines turn on would be 0 m/s^2. Therefore, the interpretation of the value on the graph before the engines turn on depends on the context and convention used in the graph.

In conclusion, the correct interpretation of the value of g-force before engines turn on is 0 g-force, as the rocket is not accelerating due to gravity. However, the term "g-force" can also be used in a more general sense to refer to any type of acceleration, in which case the value before the engines turn on could be interpreted as 1 g-force. Ultimately, it is important to consider the context and convention used in the graph to accurately interpret the value before the engines turn on.