Answer to Question #144393 in Physics for Raffy

Question

if you have a newly built boat and you tried to run it in the water and it worked.
explain the physics behind it? Don’t forget to evaluate the potential energy, kinetic energy, Newton’s Third Law of Motion, Law of Conservation of Energy.

Answer 1

I apply force to water thru oars, the water applies counter-force toward me (Newton's third law).

The potential energy in my muscles converts to kinetic energy of motion (law of conservation of energy).

At a speed of 2 m/s and if the boat weights 30 kg and my weight is 80 kg, the kinetic energy will be (and it is equal to the potential (chemical) energy of my muscles):

$$KE=PE=\frac12mv^2=220\text{ J}.$$