1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Finding Acceleration

  1. Sep 3, 2010 #1
    1. The problem statement, all variables and given/known data
    aircraft has liftoff speed of 130km/hr. What minimum constant acceleration does it require if the aircraft is to be airborne after a run of 271m? answer is in m/s^2

    2. Relevant equations
    V^2 = Vi^2 + 2a(deltax)
    a=(V^2)/Vi^2 + 2(deltax)

    3. The attempt at a solution
    (130^2)/O^2 + 2(271) = a
    a = 28.79 km/hr = 230.24 m/s^2
  2. jcsd
  3. Sep 3, 2010 #2

    Filip Larsen

    User Avatar
    Gold Member

    The 2nd equation under 2) is not correct. The first equation is ok, so you just need to be careful how you isolate a from it. You should also consider what unit of the values you will use before inserting them (hint: convert km/h to m/s before inserting the value).
  4. Sep 3, 2010 #3
    is this right then

    (V^2) - (Vi^2)/(deltax) = 2a
  5. Sep 4, 2010 #4

    Filip Larsen

    User Avatar
    Gold Member

    Close. You may mean the right thing, but as you have written it, it misses a set of parenthesis around the the two speeds. Alternatively you can insert vi=0 into the first equation before you start isolating for a.
  6. Sep 5, 2010 #5
    so if Vi = 0 then the equation is (V^2)/(deltax) = 2a and 130km/hr = 36.11 m/s so
    (36.11 m/s)^2/271m = 2a
    4.812 = 2a
    a = 2.41 m/s

    I feel like i did it right but I need the final units in m/s^2 and isn't this in m^2/s^2
  7. Sep 5, 2010 #6

    Filip Larsen

    User Avatar
    Gold Member

    The square of velocity in unit m/s has unit m2/s2 which then is divided by distance in unit m, so the resulting unit is m/s2 as it should.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Finding Acceleration
  1. Finding Acceleration (Replies: 3)

  2. Find the Acceleration (Replies: 11)

  3. Find acceleration (Replies: 4)

  4. Finding acceleration (Replies: 18)