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!

Kinematics/free fall objects help.

  1. Oct 9, 2011 #1
    In my honors course we are covering kinematics concepts. There was this problem which stumbled me but then I figured out what I did wrong. I just want to make sure my concept was right. Here is the problem...

    A diver springs upward with an intial speed of 1.8 m/s from a board that is 3 meters above
    the surface of the pool (his displacement is y = -3m). What is the highest point he reaches above the water.

    So this was my equation

    vi = 1.8 m/s
    vf = 0 m/s
    a = -9.8 m/s2
    x = ?

    Solved the equation and got x = 3.16 or 3.2

    So the part that kind of confused me in the begining was that I only had vi and vf. There had to be one more piece to solve the equation. Thats when I realized that gravity works even when the object has a positive velocity in the upward y direction. But then I started
    doubting my self so Im kind of confused.
     
  2. jcsd
  3. Oct 9, 2011 #2
    So are you confused about when to use -9.8 as the acceleration?
     
  4. Oct 9, 2011 #3
    Yeah basically. I was confused because he was going up and I kept thinking gravity in terms of falling down. So I wanted to make sure that gravity is the same when going up as well.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Kinematics/free fall objects help.
Loading...