Question

If you place the corner of a paper towel into a droplet of water, the water moves into the paper towel. Which of the following would explain the movement of the water?

a) Gravity
b) Capillary action
c) Osmosis
d) Buoyancy

Answer 1

The correct answer is b) Capillary action. Capillary action is the movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension12. Water is attracted to the fibers of the paper towel and pulls other water molecules along with it, overcoming the force of gravity12. The other options are incorrect because they are either unrelated to the phenomenon or have a negligible effect on the water movement. Gravity and buoyancy are balanced forces that do not cause water to move3. Osmosis is the movement of water across a semipermeable membrane due to a concentration gradient4, which is not the case in this scenario.

Answer 2

The movement of water into a paper towel when its corner is placed in a droplet is explained by capillary action, which is a result of adhesive and cohesive forces within the liquid and the paper towel material.

Step-by-step explanation:

When the corner of a paper towel is placed into a droplet of water and the water moves into the paper towel, the phenomenon responsible for this movement is capillary action. Capillary action occurs due to the adhesive forces between the liquid molecules and the surface of the porous material of the paper towel, as well as the cohesive forces within the liquid itself. These forces allow the liquid to flow within the porous material and can even move the liquid upward against gravity.

Capillary action is what enables liquids, like water, to wick up through the tiny spaces found in materials like paper towels and cloth. This is also observed with water rising in thin glass tubes, known as capillaries, irrespective of their angle in the liquid. Additionally, this action is crucial in nature, playing a pivotal role in transporting water from the roots to the leaves in plants and trees, contributing to vital biological processes.