Connect with us

Physics

Discussion in 'Electronics Homework Help' started by Integrator741, Mar 15, 2016.

Scroll to continue with content
  1. Integrator741

    Integrator741

    125
    4
    Jun 16, 2013
    Good Evening Everyone,

    I think I have it right - just don't have an example to double check.

    "An Object is projected vertically upwards from ground level at 49 m s^-1. Find its height after 1 s, 3 s, 5 s, 7 s, 9 s. What is its total time of flight?"

    I've answered the first part of this question using "s = ut+1/2at^2" and it seems that I got that right.
    Now, "when they say what is its total time of flight" do they mean both ways? Because the answer is 10s, but using "v=u+at" I get 5s. So if it is both ways then I am right, if not, I must have done something wrong.

    Thank you.
     
  2. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    There is no additional details regarding how it's landing. I'm sure it would be safe to assume total flight if it was shot vertically would be the time it takes to return to it's initial starting point.
     
  3. davenn

    davenn Moderator

    13,654
    1,888
    Sep 5, 2009
    and don't forget the effects of gravity acting on the object
    unless the problem specifically stated to ignore it
     
  4. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    You did fine.
    Vi=initial speed
    g=-9.8m/s^2 (gravity)

    V(t)=Vi+g*t
    at the top of the trajectory V(t)=0 ,thus
    0=Vi+g*t ,so
    t=-Vi/(-g) = Vi/9.8
    t(TOP)=49 /9.8=5sec (time to the top)

    The total time of flight is
    T(Tot)= 2*t(TOP)=10sec
     
    Integrator741 and hevans1944 like this.
  5. Integrator741

    Integrator741

    125
    4
    Jun 16, 2013
    Thank you.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-