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!

Need Help please

  1. Feb 5, 2009 #1
    1. The problem statement, all variables and given/known data

    A log is floating on swiftly moving water. A stone is dropped from rest from a 75-m high bridge and lands on the log as it passes under the bridge. If the log moves with a constant speed of 5.0 m/s, what is the horizontal distance between the log and the bridge when the stone is released?

    2. Relevant equations

    Not really sure how to start off the problem, would appreciate if anyone could help me on the problem.

    3. The attempt at a solution I tried using the equation VF^2=Vi+2a(Xf-Xi)
  2. jcsd
  3. Feb 5, 2009 #2
    A good place to start is to find the time it takes for the stone to fall those 75m. How can you relate that time to the movement of the log?
  4. Feb 5, 2009 #3
    Not really sur how to find the time when the only given information is that it is 75m high from the log. If I need to find the time I also need the velocity or acceleration. So how can I do that?
  5. Feb 5, 2009 #4


    User Avatar
    Homework Helper

    You know the height.

    You know gravity.

    x = 1/2*g*t2
  6. Feb 5, 2009 #5
    Okay so i followed the equation and got apporoximately 3.9 secs then what equation can I use next to relate to horizontal distance?
  7. Feb 5, 2009 #6


    User Avatar
    Homework Helper

    How fast again was the log moving?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Need Help please
  1. Need help please (Replies: 4)