Question

Carla makes a small cardboard boat and floats it in a tub of water. When she adds a drop of dish soap behind the boat, the boat moves forward.

Answer 1

I'm assuming that this experiment is to make the boat move with the soap? If it is, then I'll just explain how it works. What is behind the movement of the boat would be surface tension. Surface tension messes up the movement of the water molecules and attracts them, making the surface tension behind the boat decrease. Since water molecules move towards higher surface tension, then this is why the boat moves forward.

Answer 2

Answer: The soap increased the kinetic energy of the water molecules behind the boat, causing both the molecules and the boat to move forward.