Inertia and a Rocket that doesn't accelerate anymore

In summary, the conversation discusses the scenario of a rocket on an Earth-like planet without an atmosphere. The rocket initially accelerates and then stops accelerating, but still has enough speed to move away from the planet without escaping its gravity field. The "astronaut" inside the rocket will feel pressure from the rocket blast while it is accelerating, but once the engine stops, they will be in free fall and experience a feeling of weightlessness. The term "stops" refers to when the rocket engine stops providing acceleration. Regardless of the rocket's speed or distance from the planet, the "astronaut" will always feel inertia inside the rocket, but will float in a weightless environment without any atmosphere or use of thrusters.
  • #1
LM542
10
0
Let's say we are on Earth-like planet, but without an athmosphere.
There's a rocket on the ground and it's starting now. The rocket accelerates but at a point when it has enough speed it stops accelerating. The rocket has still enough speed to get further away from the planet but not enough to escape the planets gravity field.

So the rocket has stopped to accelerate but still has enough speed to get further away from the planet, does an astronaut now feel any kind of inertia? Is he floating in the rocket?
 
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  • #2
The rocket blast accelerates the rocket. It is the rocket pushing on the "astronaut" that she feels as pressure. When the rocket stops, she no longer feels that and will be in "free fall".
 
  • #3
HallsofIvy said:
The rocket blast accelerates the rocket. It is the rocket pushing on the "astronaut" that she feels as pressure. When the rocket stops, she no longer feels that and will be in "free fall".
What do you exactly mean with "stops"? When the acceleration stops or when the rocket reaches the point when it falls down back on the planet.
 
  • #4
By "the rocket stops" I meant when the rocket engine stops so there is no more acceleration. I should have said "engine". Thanks for asking so I could clarify that.
 
  • #5
LM542 said:
but still has enough speed to get further away from the planet
That does not matter, by the way.

An astronaut will always feel inertia (it takes some effort to accelerate inside the rocket), but if we have no atmosphere and the rocket is not using thrusters*, the astronaut will always float inside the rocket.

*and assuming the rocket does not have ground contact, of course
 

Related to Inertia and a Rocket that doesn't accelerate anymore

1.

What is inertia?

Inertia is the tendency of an object to resist changes in its state of motion. It is directly related to an object's mass, with objects having more mass having greater inertia.

2.

How does inertia affect a rocket that doesn't accelerate anymore?

If a rocket is not accelerating, it means that the forces acting on it are balanced, resulting in a state of equilibrium. Inertia causes the rocket to maintain its current state of motion, so if it is not accelerating, it will continue to move at a constant speed in a straight line.

3.

Why does a rocket not accelerate anymore?

A rocket may stop accelerating due to a number of factors, such as running out of fuel or encountering external forces that counteract the thrust of the rocket's engines. In either case, the forces acting on the rocket are balanced, resulting in a state of equilibrium and no further acceleration.

4.

Can a rocket with no acceleration still move?

Yes, a rocket can still move even if it is not accelerating. Inertia causes the rocket to maintain its current state of motion, so if it is moving at a constant speed, it will continue to do so until acted upon by an external force.

5.

How does inertia affect the trajectory of a rocket?

Inertia plays a crucial role in determining the trajectory of a rocket. The rocket's initial velocity and direction are determined by the forces acting on it at launch, and inertia causes it to maintain this trajectory unless acted upon by external forces, such as gravity or air resistance.

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