Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Which is the maximum speed that our human body can bear?

  1. Jul 26, 2015 #1
    The astronauts who were travelling to the space. in what way their health were affected? During the rocket launch the space craft should travel greater than the earth's escape speed. Is this speed affect the astronaut? And tell me which is the maximum speed that our human body can bear?
  2. jcsd
  3. Jul 26, 2015 #2
    Velocities can never be felt by anyone, only accelerations can. As such, only the thrust produced by the rocket engines can be responsible for anything the astronauts might 'feel'. For more information, I suggest you go through the 'Human tolerance of g-force' section in this link: https://en.m.wikipedia.org/wiki/G-force
    I assume you're only talking about the physical health effects during take-off, right? If not, then there can be some additional, often nasty side effects due to extended exposure to cosmic radiation, joint function decay from near 0 g's, and certain psychological implications due to being cut-off from regular human society leading to anxiety, depression and other effects [citation needed!].
    Last edited: Jul 26, 2015
  4. Jul 26, 2015 #3


    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    Praveena, I think the important thing is not to change speed too abruptly. PWiz already explained. As long as one increases the speed gradually it does not hurt to go very fast.

    The serious medical problems with spending long periods of time in space are:
    A. radiation. Our atmosphere protects us from the dangerous radiation out in space. Once you go outside the atmosphere you should be shielded from radiation---and it is difficult to shield completely. Radiation can cause cancer and harmful mutations.

    B. low gravity. Our bodies evolved to suit the normal Earth gravity. Normal exercise helps keep your bones strong. After many months in zero gravity--in orbit--a person may have weak bones.
    Last edited: Jul 26, 2015
  5. Jul 26, 2015 #4


    User Avatar
    Gold Member

    This is incorrect. To expand on what's already been said, the "escape speed" (more properly called the "escape velocity") is a BALLISTIC velocity. That is, it is the speed you would have to be traveling if shot from a gun at the surface of the Earth to never fall back to Earth. Rockets don't work that way. They start off at extremely slow speed, and slowly pick up speed and keep picking up speed. By the time they are far away from Earth, their "escape velocity" is much lower than it was at the surface of the Earth. Thus their acceleration is small, as has been pointed out.
  6. Jul 26, 2015 #5
    thank u pwiz
  7. Jul 26, 2015 #6
    You mean acceleration?
  8. Jul 26, 2015 #7


    User Avatar
    Science Advisor

    I remember seeing these training videos long ago. What the body can take is amazing.
  9. Jul 27, 2015 #8
    really it's a amazing video.thank u for ur help.
  10. Jul 27, 2015 #9
  11. Jul 27, 2015 #10
    Perhaps 10 g. 100m/s^2, at 7 g, aircraft pilot can go unconsious. Perhaps some mentors can give more precise number?
  12. Jul 27, 2015 #11
    I think the link which I gave in my first post can save them the trouble :wink:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook