Results 1 to 2 of 2

Math Help - Frames of reference

  1. #1
    Member
    Joined
    Mar 2007
    From
    England
    Posts
    104

    Frames of reference

    I'm very stuck on this question:

    In a road accident at cross-roads, a car of mass 1250kg traveling at a speed of 40km/h from west to east hits a truck of mass 4000kg traveling at a speed of 30km/h from North to South. The vehicles lock together and skid off the road.
    Consider the situation just before the collision from two different point of views of the pilot of a helicopter:
    i)hovering above the intersection
    ii) flying parallel to, and keeping pace with the car
    In each case, find the direction and speed of the vehicles after the collision.

    I wanted to use conservation of linear momentum to solve the question, but the two vehicles are not traveling in a line so I don't know how to adapt the equation, and for the second case I did 30*4000=(1250+4000)v, and v came out to be 22.857km/h, which is the wrong answer (correct answer would have been 38.1km/h at 233 degrees)

    Any help would be hugely appreciated.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by free_to_fly View Post
    I'm very stuck on this question:

    In a road accident at cross-roads, a car of mass 1250kg traveling at a speed of 40km/h from west to east hits a truck of mass 4000kg traveling at a speed of 30km/h from North to South. The vehicles lock together and skid off the road.
    Consider the situation just before the collision from two different point of views of the pilot of a helicopter:
    i)hovering above the intersection
    ii) flying parallel to, and keeping pace with the car
    In each case, find the direction and speed of the vehicles after the collision.

    I wanted to use conservation of linear momentum to solve the question, but the two vehicles are not traveling in a line so I don't know how to adapt the equation, and for the second case I did 30*4000=(1250+4000)v, and v came out to be 22.857km/h, which is the wrong answer (correct answer would have been 38.1km/h at 233 degrees)

    Any help would be hugely appreciated.
    Momentum is a vector quantity, so what is conserved in the collision is:

    \bold{p}=m_1 \bold{v}_1+m_2 \bold{v}_2

    where \bold{v}_1 and \bold{v}_2 are the vector velocities of the two vehicles in whatever reference frame is being considered.

    CB
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. frames of a hilbert space
    Posted in the Differential Geometry Forum
    Replies: 1
    Last Post: April 3rd 2011, 12:25 AM
  2. [SOLVED] Rotation Matrix Conversion in Two Frames of Reference
    Posted in the Advanced Algebra Forum
    Replies: 0
    Last Post: March 24th 2011, 07:12 AM
  3. Probability in different time frames
    Posted in the Statistics Forum
    Replies: 0
    Last Post: February 9th 2010, 08:01 PM
  4. constructing wire frames
    Posted in the Statistics Forum
    Replies: 2
    Last Post: August 7th 2007, 02:58 AM
  5. Picture Frames
    Posted in the Algebra Forum
    Replies: 3
    Last Post: July 6th 2007, 01:17 PM

Search Tags


/mathhelpforum @mathhelpforum