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!

Please Help: Ball intersection problem

  1. Sep 17, 2007 #1
    1. A ball is thrown upward from the ground with an initial speed of 25m/s. At the same instant, a ball is dropped from rest from a building 15m high. After how long with the balls be at the same height?



    2. The equation i had in mind was D=Vi(t) + 1/2 at^2



    3. For this problem I believe that I have to set two sets of the above equation equal to each other since distance or time for both of the balls have to be equal. However I do not know how to do this exactly.

    edit: I just realized there was another post on this problem, however i could not find help on it. Also as a side question, my physics teacher said a bonus question on our upcoming test will be what happens to all the outcomes of equations including time if time is an imaginary number. I told him that they would become zero or decrease or become negative and said i was wrong. Any thoughts about this? To me, an imaginary number is the square root of a negative number.
     
    Last edited: Sep 17, 2007
  2. jcsd
  3. Sep 17, 2007 #2

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    Almost - that's probably the correct equation
    Remember that the distance for one of the balls is (15-D) depending on which level you want to use as zero and note that a is the same sign for both.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Please Help: Ball intersection problem
Loading...