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

Homework Help: Very likely a stupid question =S Finding acceleration with formula V^2=u^2+2*a*d

  1. Jun 2, 2010 #1
    1. The problem statement, all variables and given/known data

    racing driver, David Purley, survived a deceleration from 173km/h to 0km/h in a distance of 66cm in a crash. body mass = 55kg
    2. Relevant equations

    V^2=u^2+2*a*d is what i have to work with at the moment, i was thinking of using a=Fnet/mass. but im having trouble finding the Fnet.

    3. The attempt at a solution

    honestly, i dont know where to start.
     
  2. jcsd
  3. Jun 2, 2010 #2

    CompuChip

    User Avatar
    Science Advisor
    Homework Helper

    In the formula you gave,
    [tex]v^2 = u^2 + 2ad[/tex]
    what do all the letters mean?
    I.e. what does v stand for, and u, and a and d?
    Can you also list for which ones values are given in the problem and which ones are still unknown?
     
  4. Jun 2, 2010 #3
    um, the only variables and values they gave me are, the mass of the driver '55kg', the initial velocity '173 km/h' final velocity '0km/h' and the stopping distance '66cm'
    i understand that there are a few other things which may help, but thats all he gave us
    v=final velocity
    u=initial velocity
    a=acceleration
    d=distance


    sorry about this, this is my first post on here and yeah, sorry mate.
     
  5. Jun 2, 2010 #4

    CompuChip

    User Avatar
    Science Advisor
    Homework Helper

    Look closely at the two lists.
    Seems to me that the formula is very useful... there is just one unknown quantity in there, isn't it?
     
  6. Jun 5, 2010 #5
    yeah, my main problem is i dont know how to rearrange the formula =S
     
  7. Jun 5, 2010 #6

    CompuChip

    User Avatar
    Science Advisor
    Homework Helper

    OK, what formula do you get when you plug in all the given values?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook