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!

How long does it take the particle to hit the y-axis?

  1. May 17, 2009 #1
    1. When a particle is at the origin, it has a velocity given by vo = (12i + 15j)ms-1. It has a constant acceleration given by a = (-1.5i + 0.25j) ms-2.
    (a) How long does it take the particle to hit the y-axis?
    (b) At what point does it hit the y-axis?
    (c) What is its velocity at the instant it hits the y-axis?




    2. Not certain what to use or how to get started. I have never seen nor done a problem like this before. Please help.



    3. Not certain what to use or how to get started. I have never seen nor done a problem like this before. Please help.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 17, 2009 #2

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    This is just a projectile type question, written in vector form. Can you solve projectile questions? If so, then just start out as usual: draw a diagram, then write out the quantities you know in the vertical and horizontal directions, and what you want to find out. Then use an appropriate equation for kinematic motion to solve.

    Show some work, and we can help you.
     
  4. May 17, 2009 #3
    i'm still very xtremely confused, i honestly don't know how to start it at all
     
  5. May 17, 2009 #4
    for the velocity it would be the square root of 15^2 + 12^2? which would be 19? and then for acceleration it would be the sqaure root of -1.5^2 + 0.25^2? which would be 1.5? am I completely off track?
     
  6. May 17, 2009 #5
    so no way to help get me started?
     
  7. May 17, 2009 #6

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    You just split things up into x and y components. So, the particle is at x=0, with u_x=12, a_x=-1.5; and at y=0, with u_y=15, a_y=0.25.

    What is the x coordinate of the particle when it hits the y axis? Can you construct an equation in terms of x coordinates which will allow you to obtain t?
     
  8. Sep 26, 2011 #7
    I was actually about to ask the exact question. In this case, would it be sufficient to use only the x component for the acceleration and velocity, since in fact, the particle will hit the y-axis at x=o? I used the function x=x_0+v_xo t+1/2at^2. Then plugged my v_xo value(12ms^-1), my constant acceleration in the x direction(-1.5ms^-2). Then solved for t. Leaving me with t=0s(when the particle started at origin), and t=16s. Does this look about right?
     
    Last edited: Sep 26, 2011
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: How long does it take the particle to hit the y-axis?
Loading...