The initial kinetic energy of the boat and its rider is
After Sam stops it, the final kinetic energy of the boat+rider is
because its final velocity is zero.
For the law of conservation of energy, the work done by Sam is the variation of kinetic energy of the system:
where the negative sign is due to the fact that the force Sam is applying goes against the direction of motion of the boat.
After Sam stops it, the final kinetic energy of the boat+rider is
because its final velocity is zero.
For the law of conservation of energy, the work done by Sam is the variation of kinetic energy of the system:
where the negative sign is due to the fact that the force Sam is applying goes against the direction of motion of the boat.