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!

Motion of an object dropped from a descending and ascending helicopter

  1. Jul 29, 2013 #1
    1.
    a) A small mail bag is released from a helicopter that is descending steadily at 3.34 m/s. After 2.95 s, what is the speed of the mailbag? The acceleration of gravity is 9.8 m/s2 . Answer in units of m/s

    b) After the mailbag is dropped, the helicopter continues descending for 1 s but then stops. How far is the mailbag below the helicopter at 2.95 s? Answer in units of m

    c) What would be the speed of the mailbag if the helicopter had been rising steadily at u = 3.34 m/s ? (Take down as positive.) Answer in units of m/s


    2. vf = vi + at


    3. I've already gotten the answer to a) which is 32.25m/s, but I do not know how to do b) or c) from my answer to a).
     
  2. jcsd
  3. Jul 29, 2013 #2

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    For b), you need a kinematic equation (valid for constant acceleration) that involves distance (usually denoted s). Do you have any such?

    c) is exactly the same as a) but with a different vi.
     
  4. Jul 29, 2013 #3
    would this equation be appropriate for b) s=vi*t+1/2*at2
     
    Last edited: Jul 29, 2013
  5. Jul 29, 2013 #4
    For c) would I use -3.34 as the vi?
     
  6. Jul 29, 2013 #5
    Thanks for the help, I've got c) correct but am still confused about b).
     
  7. Jul 29, 2013 #6
    Find s for both objects, what is the difference?

    Note that the helicopter is not in free fall... Descending steadily...

    I am assuming that the helicopter does not undergo a constant acceleration up during the 1s. The way it is written implies to me the helicopter stops instantaneously after 1s.
     
    Last edited: Jul 29, 2013
  8. Jul 29, 2013 #7
    Thanks, looks like I missed the obvious. I got the correct answer now.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Motion of an object dropped from a descending and ascending helicopter
Loading...