AQA M3 2008 June — Question 2

Exam BoardAQA
ModuleM3 (Mechanics 3)
Year2008
SessionJune
TopicVectors Introduction & 2D

2 The unit vectors \(\mathbf { i }\) and \(\mathbf { j }\) are directed due east and due north respectively.
Two runners, Albina and Brian, are running on level parkland with constant velocities of \(( 5 \mathbf { i } - \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 1 }\) and \(( 3 \mathbf { i } + 4 \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 1 }\) respectively. Initially, the position vectors of Albina and Brian are \(( - 60 \mathbf { i } + 160 \mathbf { j } ) \mathrm { m }\) and \(( 40 \mathbf { i } - 90 \mathbf { j } ) \mathrm { m }\) respectively, relative to a fixed origin in the parkland.
  1. Write down the velocity of Brian relative to Albina.
  2. Find the position vector of Brian relative to Albina \(t\) seconds after they leave their initial positions.
  3. Hence determine whether Albina and Brian will collide if they continue running with the same velocities.