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
The force exerted on the board by the karate master given the data is -4500 N
<h3>Data obtained from the question </h3>
- Initial velocity (u) = 10 m/s
- Final velocity (v) = 1 m/s
- Time (t) = 0.002 s
- Mass (m) = 1 Kg
- Force (F) = ?
<h3>How to determine the force</h3>
The force exerted can be obtained as illustrated below:
F = m(v - u) / t
F = 1 (1 - 10) / 0.002
F = (1 × -9) / 0.002
F = -4500 N
Learn more about momentum:
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Earth Spheres. Earth's Spheres. Everything in Earth's system can be placed into one of four major subsystems: land, water, living things, or air. These four subsystems are called “spheres.” Specifically, they are the lithosphere (land), hydrosphere (water), biosphere (living things), and atmosphere (air).
