Answer:
-1.43 m/s relative to the shore
Explanation:
Total momentum must be conserved before and after the run. Since they were both stationary before, their total speed, and momentum, is 0, so is the total momentum after the run off:
where are the mass of the swimmer and raft, respectively.
are the velocities of the swimmer and the raft after the run, respectively. We can solve for
So the recoil velocity that the raft would have is -1.43 m/s after the swimmer runs off, relative to the shore