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

Click For Summary

Discussion Overview

The discussion revolves around determining the maximum velocity of an object subjected to a constant force in a vacuum, specifically considering a scenario involving a rock and a hypothetical character applying force. The focus includes theoretical implications of Newtonian and relativistic physics.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant presents a scenario where a 100lbs force is applied to a 100lbs rock in a vacuum, questioning how long it would take to reach maximum velocity and what that velocity would be.
  • Another participant emphasizes that the speed of light is the ultimate speed limit, suggesting that the rock's speed would approach but never reach this limit according to relativity.
  • Some participants argue about the implications of applying a constant force without considering fuel limitations, while others point out that the scenario's assumptions may not align with physical principles.
  • There is a contention regarding the appropriateness of discussing hypothetical scenarios in a technical forum, with some participants advocating for open-mindedness while others insist on sticking to established physics.

Areas of Agreement / Disagreement

Participants express differing views on the validity of the scenario presented, with some insisting on the constraints of physics while others attempt to explore the implications of the hypothetical situation. The discussion remains unresolved regarding the appropriateness of the scenario and its implications.

Contextual Notes

The discussion highlights limitations in the assumptions made about constant force application and the implications of relativistic physics, which were not fully addressed by all participants.

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.
 
Last edited by a moderator:
Physics news on Phys.org
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. :smile:
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.
 
Last edited:
be open minded please. its just a way to say that object A is ONLY limited by object B. and how much.
 
matliolec said:
be open minded please.
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.
 
  • Like
Likes   Reactions: 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.
 
Thread closed for Moderation...
 
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.
 

Similar threads

Undergrad Express drag force/acceleration/velocity as function of time
  • · Replies 14 ·
Replies
14
Views
2K
High School How will object's velocity change when a frictional force increases?
  • · Replies 16 ·
Replies
16
Views
2K
Undergrad An actual meaning of instantaneous velocity
  • · Replies 13 ·
Replies
13
Views
2K
High School Questions about momentum and force as well as normal force/friction
  • · Replies 35 ·
2
Replies
35
Views
5K
High School What is the maximum velocity of object A if its weight is doubled?
  • · Replies 4 ·
Replies
4
Views
1K
Undergrad What is the maximum velocity of a bullet at the instant it leaves the barrel?
  • · Replies 5 ·
Replies
5
Views
5K
High School Understanding Momentum: The Relationship Between Mass, Velocity, and Force
  • · Replies 29 ·
Replies
29
Views
3K
High School What is the relationship between force (in lbs) and speed?
  • · Replies 35 ·
2
Replies
35
Views
9K
Undergrad Force problem - how the force interacts with time
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Impact, momentum, demand and capacity
  • · Replies 5 ·
Replies
5
Views
2K