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

Acceleration question.

  1. Oct 11, 2006 #1
    In 1865, Jules Verne proposed sending men to the Moon by firing a space capsule from a 220 m long cannon with final velocity of 10.78 km/s. What would have been the unrealistically large acceleration experienced by the space travelers during launch?

    The answer needs to be in

    Number times g.
    g = 9.81

    I tried v^2 = 1/2(a)(220)
    So v^2 = 110
    Square root of 110 = 10.48..
    Not correct..

    Don't know what to do.
  2. jcsd
  3. Oct 11, 2006 #2


    User Avatar
    Science Advisor
    Homework Helper

    Don't throw away the (a) going from the first to the second line, and use the given information to calculate v^2. Then solve for (a) and express as a fraction of g. Also, check your first equation. It is not correct.
    Last edited: Oct 11, 2006
  4. Oct 11, 2006 #3

    Right so 10,780^2 is the final velocity since the first one is in k/m?

    10,780^2 = 1/2(a)(220)
    10,780^2 = 110a
    A = 1056440
    Divided by 9.81..


    Still incorrect.
  5. Oct 11, 2006 #4


    User Avatar
    Science Advisor
    Homework Helper

    Perhaps because your equation is still incorrect, and you have not expressed a as a multiple of g.
  6. Oct 11, 2006 #5
    Can I not just divide the acceleration by g at the end and get the same answer?
  7. Oct 11, 2006 #6
    bump..due in an hour 20 minutes ;)
  8. Oct 11, 2006 #7
    Nevermind, got this one.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook