Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Linear Motion Homework Problem

  1. Feb 28, 2008 #1
    1. The problem statement, all variables and given/known data
    You adjust your garden hose nozzle for a hard stream of water. You point the nozzle vertically upward at a height of 1.5m above the ground. When you quickly move the nozzle away from the vertical, you hear the water striking the ground next to you for 2.0 s. What is the water speed as it leaves the nozzle?

    2. Relevant equations
    I'm guessing, d = v2t-(0.5)at^2
    and v1^2= (v2^2)-2ad.

    3. The attempt at a solution
    I subbed in v2=0, a = -9.8, and t= 2.0 in the first equation to get distance.

    And then subtracted 1.5 from the distance and used the new distance in the second equation (v1^2= v2^2 -2ad) to find velocity and came up with 18.84m/s.

    It's not right because I had no idea which distance to use or how to find the right distance because the time value of 2.0 seconds is confusing me (the wording, anyways).

    Should distance be -1.5m instead? :S
  2. jcsd
  3. Mar 1, 2008 #2

    Shooting Star

    User Avatar
    Homework Helper

    That's right. The water which leaves the nozzle with a speed of vi upward takes 2 secs to fall -1.5 m from the starting point, if up is taken as positive. Be careful about the signs of the other quantities.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook