SIN Bin: 1978, Problem 13

By Department Faculty

Problem

Two identical hard, smooth, spherical space ships abandoned by Captain Kirk in outer space are at rest and just touching each other at one common point. A third identical ship, piloted by Spock coasts in along the common tangent as shown. Just before it simultaneously collides with the two abandoned ships, the third ship has velocity of +20 km/sec in the obvious direction. What is the velocity of the third ship just after collision? (Assume no rocket thrust or time warp, assume only elastic collision forces, be liberal with use of symmetry but conservative with momentum and energy.) (Answers in km/sec).

1. +10
2. +4
3. 0
4. -4
5. -10