# What is the top velocity of an object with a certain force applied in a vacuum?

• matliolec
In summary, the conversation discussed a scenario where an object, A, is being pushed by another object, B, with a constant force in a vacuum. There was a question about the maximum velocity that object A can reach and whether or not object B, with superhuman abilities, can push it to infinite speed. The conversation also mentioned the limitations of Newtonian physics and the concept of fuel supply in relation to acceleration. The conversation was ultimately closed due to the discussion of fantasy elements and the thread being deemed inappropriate for the PF.
matliolec
ok i have a simple enough scenario that i need a hand with solving. first off just to say, i don't know how to do the math for it so maybe someone here could help me out.

basically has to do with finding the top velocity of an object with a certain force applied. all in a vacuum and without any form of resistance of course.

so let's say object A (a cubic foot rock, at a 100lbs in weight on earth) is motionless in space. and object B applies a 100lbs of force on the rock for a tenth of a second every 5 seconds..

oh and as the mass of the rock increase with speed the time between applied force will also decrease.

how long will it take to reach its maximum velocity and how fast will object A and the rock (object B) be going with it pushing on the rock at all time.

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matliolec said:
ok i have a simple enough scenario that i need a hand with solving. first off just to say, i don't know how to do the math for it so maybe someone here could help me out.

basically has to do with finding the top velocity of an object with a certain force applied. all in a vacuum and without any form of resistance of course.

so let's say object A (a cubic foot rock, at a 100lbs in weight on earth) is motionless in space. and object B (superman.. but this one can go infinitly fast.. but rather weak) applies a 100lbs of force on the rock for a tenth of a second every 5 seconds..

oh and as the mass of the rock increase with speed the time between applied force will also decrease.

he can't apply more then a 100lbs of force.. how long with it take to reach its maximum velocity and how fast will Mr superman and the rock be going with him push on the rock at all time.

Welcome to the PF.
matliolec said:
superman.. but this one can go infinitly fast..
No can do. The speed of light "c" is the upper speed limit -- extremely energetic particles can get very close to c, but never reach it.

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be open minded please. its just a way to say that object A is ONLY limited by object B. and how much.

matliolec said:
No can do. We don't discuss fantasy in the technical PF forums.

fine then. edited. one moment.

If Newtonian physics were true its speed relative to its starting frame would tend to infinity. It's not true, though, and in relativity the answer is that its speed will tend towards, but never reach, c relative to its starting frame.

In practice the speed would be limited by the fuel supply of whatever was doing the accelerating. When it runs out you can't accelerate any more.

berkeman
Ibix said:
If Newtonian physics were true its speed relative to its starting frame would tend to infinity. It's not true, though, and in relativity the answer is that its speed will tend towards, but never reach, c relative to its starting frame.

In practice the speed would be limited by the fuel supply of whatever was doing the accelerating. When it runs out you can't accelerate any more.
huh? who said anything about fuel. did u read it? no fuel, constant applied force.

matliolec said:
huh? who said anything about fuel. did u read it? no fuel, constant applied force.
As I mentioned, we do not discuss fantasy in the technical forums. And there are limitations for what can be discussed in the SciFi section of the PF as well. @Ibix was trying to help you understand the simple Special Relativity considerations behind your question.

This thread is not appropriate for the PF and is closed.

## 1. What is the formula for finding the top velocity of an object in a vacuum?

The formula for finding the top velocity of an object with a certain force applied in a vacuum is v = √(2F/m), where v is the top velocity, F is the applied force, and m is the mass of the object.

## 2. How does the absence of air affect the top velocity of an object?

In a vacuum, there is no air resistance, which means there are no external forces acting on the object. This allows the object to reach its maximum velocity without any hindrance from air resistance.

## 3. Is the top velocity of an object in a vacuum affected by its mass?

Yes, the top velocity of an object in a vacuum is directly proportional to its mass. This means that the larger the mass of the object, the lower the top velocity will be for a given force applied.

## 4. How does the applied force affect the top velocity of an object in a vacuum?

The applied force has a direct effect on the top velocity of an object in a vacuum. The greater the force applied, the higher the top velocity will be. This is because the force is directly related to the acceleration of the object, which in turn affects its velocity.

## 5. Can the top velocity of an object in a vacuum be greater than the speed of light?

No, according to Einstein's theory of relativity, the speed of light (299,792,458 m/s) is the ultimate speed limit in the universe. Therefore, the top velocity of an object in a vacuum cannot exceed the speed of light.

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