1. Not finding help here? Sign up for a free 30min 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!

Physics problem I cant get

  1. Sep 4, 2004 #1
    1.5 = (0.25 m/s)t +(0.48m/s2 )t 2

    How do I find what t is???

    If you know can you please show me how to do this!!!

    This question is relating to a Physics problem that my lab group is stump on

    My Aim is Atarikid4000, Thanks. :smile:
  2. jcsd
  3. Sep 4, 2004 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    You have 0.48 t2+ 0.25 t- 1.5= 0.

    In general, at2+ bt+ c= 0 has solutions
    [tex]t= \frac{-b+\sqrt{b^2-4ac}}{2a}[/tex] and
    [tex]t= \frac{-b-\sqrt{b^2-4ac}}{2a}[/tex].

    In your problem, a= 0.48, b= 0.25, c= -1.5.
    Last edited: Sep 4, 2004
  4. Sep 4, 2004 #3
    I recommend writing a program in your graphing calculator that automatically will solves using the quadratic formula. Saves time.

    My $.02

    Paden Roder
  5. Sep 4, 2004 #4
    Thanks for the help!!!! :smile:
  6. Sep 4, 2004 #5


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    One more thing:

    You probably already "got most of the physics" when you arrived at that equation (assuming it's correct)! [That's great!] Given your equation, "solving for t" is a math problem... not a physics problem. The only physics is deciding which of the two roots to accept for your answer.

    I tell my students to try to distinguish
    "problems with physics" (e.g., what is going on?, how do I set up the problem?, am I using the appropriate physical laws and definitions?, how do I interpret my answer?)
    "problems with math" (e.g., how do I solve for x?, what is the volume of a cylinder?, should I use sin or cos?, what is the x-component of this vector?).
    This helps the student (and me) zero-in on where the real problems lie.

    (It's a peeve of mine that "physics" is often mistakenly blamed for problems in math.)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Physics problem I cant get
  1. I cant get started (Replies: 1)