Results 1 to 6 of 6

Thread: collision

  1. #1
    Member
    Joined
    May 2016
    From
    Ireland
    Posts
    199
    Thanks
    2

    collision

    if boat x has position 2 i 7 j and velocity 4 i 5 j and boat y has position 6 i 9 j and velocity 3 i 4 j prove they are on a collision course .

    im trying to do this by finding there relative positions and velocities. im trying to make use of if they are on a collision course their velocities in the direction perpendicular to them in the j direction must be equal
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    15,520
    Thanks
    3388

    Re: collision

    if boat x has position 2 i 7 j and velocity 4 i 5 j and boat y has position 6 i 9 j and velocity 3 i 4 j prove they are on a collision course .
    do all the positions and velocities have strictly positive components? (I don't see any + or - signs)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Apr 2005
    Posts
    18,760
    Thanks
    2676

    Re: collision

    Quote Originally Posted by markosheehan View Post
    if boat x has position 2 i 7 j and velocity 4 i 5 j and boat y has position 6 i 9 j and velocity 3 i 4 j prove they are on a collision course .
    So at any time, t, boat x has position vector <2, 7>+ t<4, 5>= <2+ 4t, 7+ 5t>.
    And boat y has position vector <6, 9>+ t<3, 4>= <6+ 3t, 9+ 4t>. Is there any time, t, such that those two positions are the same? That is, is there one value of t such that 2+ 4t= 6+ 3t and 7+ 5t= 9+ 4t? It should be easy to solve the first equation for t, then substitute that value of t to check if it also satisfies the second equation.

    im trying to do this by finding there relative positions and velocities. im trying to make use of if they are on a collision course their velocities in the direction perpendicular to them in the j direction must be equal
    In "their velocities in the direction perpendicular to them", what does "them" refer to?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    May 2016
    From
    Ireland
    Posts
    199
    Thanks
    2

    Re: collision

    Sorry ye all their velocities and displacements are positive. Ye I know how to solve for the time when they collide but is there a way just to prove they will collide
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    Joined
    Nov 2013
    From
    California
    Posts
    5,392
    Thanks
    2286

    Re: collision

    Quote Originally Posted by markosheehan View Post
    Sorry ye all their velocities and displacements are positive. Ye I know how to solve for the time when they collide but is there a way just to prove they will collide
    not really. The courses could cross without collision. You have to ensure that the positional intersection of the courses occurs at the same time for a collision to occur so one way or the other you're going to need that time.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor

    Joined
    Apr 2005
    Posts
    18,760
    Thanks
    2676

    Re: collision

    Quote Originally Posted by markosheehan View Post
    Sorry ye all their velocities and displacements are positive. Ye I know how to solve for the time when they collide but is there a way just to prove they will collide
    You say "I know how to solve for the time when they collide". So do that! If there is such a time then they will collide!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Collision Result
    Posted in the Math Topics Forum
    Replies: 5
    Last Post: Jan 29th 2016, 09:41 AM
  2. Collision Result
    Posted in the Calculus Forum
    Replies: 1
    Last Post: Jan 28th 2016, 06:46 PM
  3. impact of collision
    Posted in the New Users Forum
    Replies: 0
    Last Post: Oct 1st 2015, 04:01 PM
  4. Collision question.
    Posted in the Math Topics Forum
    Replies: 9
    Last Post: May 6th 2011, 01:32 AM
  5. Before collision/after collision
    Posted in the Math Topics Forum
    Replies: 0
    Last Post: May 6th 2010, 06:24 PM

/mathhelpforum @mathhelpforum