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Can we reach the speed of light in vacuum?

  1. Jul 9, 2015 #1
    As we known, the force applied to the plane that fly in the atmosphere is to keep plane moving forward. The force given is to against the pressure of the air. If a space aircraft flies in the vacuum, the force given to it will accelerate aircraft because there is no friction caused by air pressure. Hence, the speed of aircraft will keep increasing. if we keep to give force to the aircraft, can the aircraft reach the speed of light?
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  3. Jul 9, 2015 #2


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    If you put an aircraft in a vacuum it would not be able to accelerate at all!
  4. Jul 9, 2015 #3


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    No, the inertia of an objec increases with its velocity.
  5. Jul 9, 2015 #4
    Hi Firin welcome to Physicsforums. :smile:

    As measured from Earth, you could almost reach the speed of light with a spacecraft.
    An infinite amount of energy would be needed to get it to reach exactly the speed of light.
  6. Jul 10, 2015 #5
    Thanks for all your comment.
  7. Jul 10, 2015 #6
    Come on, this is not the point PeroK. :smile:
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