OCR Further Mechanics AS 2020 November — Question 6

Exam BoardOCR
ModuleFurther Mechanics AS (Further Mechanics AS)
Year2020
SessionNovember
TopicMomentum and Collisions 2

6 Three particles \(A , B\) and \(C\) are free to move in the same straight line on a large smooth horizontal surface. Their masses are \(3.3 \mathrm {~kg} , 2.2 \mathrm {~kg}\) and 1 kg respectively. The coefficient of restitution in collisions between any two of them is \(e\). Initially, \(B\) and \(C\) are at rest and \(A\) is moving towards \(B\) with speed \(u \mathrm {~ms} ^ { - 1 }\) (see diagram). \(A\) collides directly with \(B\) and \(B\) then goes on to collide directly with \(C\).
\includegraphics[max width=\textwidth, alt={}, center]{0501e5a4-2137-4e7d-98ff-2ee81941cbf3-4_221_1342_552_246}
  1. The velocities of \(A\) and \(B\) immediately after the first collision are denoted by \(\mathrm { v } _ { \mathrm { A } } \mathrm { ms } ^ { - 1 }\) and \(\mathrm { V } _ { \mathrm { B } } \mathrm { ms } ^ { - 1 }\) respectively.
    • Show that \(\mathrm { v } _ { \mathrm { A } } = \frac { \mathrm { u } ( 3 - 2 \mathrm { e } ) } { 5 }\).
    • Find an expression for \(\mathrm { V } _ { \mathrm { B } }\) in terms of \(u\) and \(e\).
    • Find an expression in terms of \(u\) and \(e\) for the velocity of \(B\) immediately after its collision with \(C\).
    After the collision between \(B\) and \(C\) there is a further collision between \(A\) and \(B\).
  2. Determine the range of possible values of \(e\).