Pressure Required to propel something a long distance

  • #1

Summary:

Examples in thread. How much pressure does it take to propel someone or something a long distance? How much pressure does it take to shatter bone?

Main Question or Discussion Point

I am making this (hopefully in the correct forum) because I started debating propulsion about objects and the like. The main two questions I want to have answered if at all possible are as follows:

How much pressure would be needed to send a person flying?

How much pressure is needed to shatter a bone, or at least crack it?

Examples to better explain the questions: (I will specify statistics like height, weight, and other factors)

* For sending a person flying, a person around 5'10", 154 lbs, with his arm outstretched to its full extent. from the point of an inch away from the palm, an explosion is created in that bit of air, like a jet engine, the outward facing force shoots away from the person, but there is an inward for like the jet engine, is actually a rocket. Like pressure pushes the rocket out the way it is pointed, but there is still force coming out the opposite way. For that opposite, excess force, what would the pressure have to be, to send the above stated man back about 10 feet. The excess force doesn't hit his entire body, it is centered on his palm, but still send him backwards.

* Same person, same outstretched arm, same variables, same thing happens, but what ends up happening to the bones in his arm leading to his shoulder blade specifically? To add onto that though as another side example, a new variable. The man's bones have the same density and strength as military grade steel, but are easier to warp with heat, and now, there is an extreme amount of heat involved (around 200 degrees Fahrenheit)

(This may sound like I am going to attempt to harm someone or myself by experimenting, I would like to clarify that that is not the case, I am just interested in this type of stuff from time to time)
 

Answers and Replies

  • #2
.Scott
Homework Helper
2,547
916
Pushing a person's hand is a very inefficient and typically impractical way of getting the person to fly 10 feet.
So let's say we apply that force closer to the center of gravity for the person - say the lower rib cage while the person has their legs retracted.

Let's say that we are applying this force with a small rocket that is pushing against a circular spot on that persons rib cage that is exactly 1 square inch in area. And let's say that the person is face down - so the rocket is pushing him straight up.

In this configuration, the rocket will need to push 154 pounds to overcome gravity and fully support the weight of that person. Since this force is applied to a 1 square inch, the pressure would be 154 psi.

But you want the person to go "flying". Technically, at 155psi, the person would begin to accelerate upwards - eventually reaching a height of 10 feet. So 155psi would do it.

Similarly, maintaining a 155psi pressure on that person would eventually result in that person reaching an altitude of hundreds or thousands of feet. Then just turn off the rocket and you will have plenty of broken bones.

I know this isn't exactly what you were expecting in the way of a response. But perhaps you can be more specific in your scenario - it's pretty hard to address it the way you posed the problem.
 
  • Like
Likes OriginalH1h
  • #3
Pushing a person's hand is a very inefficient and typically impractical way of getting the person to fly 10 feet.
So let's say we apply that force closer to the center of gravity for the person - say the lower rib cage while the person has their legs retracted.

Let's say that we are applying this force with a small rocket that is pushing against a circular spot on that persons rib cage that is exactly 1 square inch in area. And let's say that the person is face down - so the rocket is pushing him straight up.

In this configuration, the rocket will need to push 154 pounds to overcome gravity and fully support the weight of that person. Since this force is applied to a 1 square inch, the pressure would be 154 psi.

But you want the person to go "flying". Technically, at 155psi, the person would begin to accelerate upwards - eventually reaching a height of 10 feet. So 155psi would do it.

Similarly, maintaining a 155psi pressure on that person would eventually result in that person reaching an altitude of hundreds or thousands of feet. Then just turn off the rocket and you will have plenty of broken bones.

I know this isn't exactly what you were expecting in the way of a response. But perhaps you can be more specific in your scenario - it's pretty hard to address it the way you posed the problem.
No this is a great response it answered another question that I was building in my mind.
 

Related Threads on Pressure Required to propel something a long distance

Replies
2
Views
537
Replies
2
Views
2K
Replies
4
Views
12K
Replies
2
Views
1K
Replies
17
Views
204
Replies
1
Views
3K
Replies
5
Views
681
Replies
4
Views
3K
Replies
12
Views
4K
Top