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. which statement best explaining what happened? the soap increased the viscosity of the water behind the boat, allowing the water in front of the boat to flow more easily. the soap reduced the surface tension behind the boat, causing both water molecules and the boat to be pulled forward. the soap increased the kinetic energy of the water molecules behind the boat, causing both the molecules and the boat to move forward. the soap formed an immiscible layer on the water, causing the soap to spread out and push the boat forward.

Explanation:

Dish soap reduces the surface tension of water. When added behind the boat, the higher surface tension in front (where water has normal surface tension) pulls the boat forward as the water behind has lower surface tension (due to soap) and doesn't pull as much. Option 2 (The soap reduced the surface tension behind the boat, causing both water molecules and the boat to be pulled forward) explains this: the front water's higher surface tension pulls the boat forward as the soap lowers tension behind, creating a net forward pull. Other options are incorrect: soap doesn't increase viscosity (option 1 wrong), doesn't increase kinetic energy to move molecules/boat (option 3 wrong), and soap is miscible in water (option 4 wrong about immiscible layer).

Answer:

The soap reduced the surface tension behind the boat, causing both water molecules and the boat to be pulled forward. (Assuming the second option is labeled as, e.g., B. The soap reduced the surface tension behind the boat, causing both water molecules and the boat to be pulled forward)