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Mar 20, 2023 · Published 3:54 PM PDT, March 20, 2023. BERLIN (AP) — Humanity still has a chance, close to the last, to prevent the worst of climate change’s future harms, a top United Nations panel of scientists said Monday. But doing so requires quickly slashing nearly two-thirds of carbon pollution by 2035, the Intergovernmental Panel on Climate Change ...
- Overview
- Cohesion of water
- Adhesion of water
Cohesion, adhesion, and surface tension of water and how they relate to hydrogen bonding.
Have you ever filled a glass of water to the very top and then slowly added a few more drops? Before it overflows, the water forms a dome-like shape above the rim of the glass. This dome-like shape forms due to the water molecules’ cohesive properties, or their tendency to stick to one another. Cohesion refers to the attraction of molecules for other molecules of the same kind, and water molecules have strong cohesive forces thanks to their ability to form hydrogen bonds with one another.
Cohesive forces are responsible for surface tension, a phenomenon that results in the tendency of a liquid’s surface to resist rupture when placed under tension or stress. Water molecules at the surface (at the water-air interface) will form hydrogen bonds with their neighbors, just like water molecules deeper within the liquid. However, because they are exposed to air on one side, they will have fewer neighboring water molecules to bond with, and will form stronger bonds with the neighbors they do have. Surface tension causes water to form spherical droplets and allows it to support small objects, like a scrap of paper or a needle, if they are placed carefully on its surface.
Water likes to stick to itself, but under certain circumstances, it actually prefers to stick to other types of molecules. Adhesion is the attraction of molecules of one kind for molecules of a different kind, and it can be quite strong for water, especially with other molecules bearing positive or negative charges.
For instance, adhesion enables water to “climb” upwards through thin glass tubes (called capillary tubes) placed in a beaker of water. This upward motion against gravity, known as capillary action, depends on the attraction between water molecules and the glass walls of the tube (adhesion), as well as on interactions between water molecules (cohesion).
The water molecules are more strongly attracted to the glass than they are to other water molecules (because glass molecules are even more polar than water molecules). You can see this by looking at the image below: the water extends highest where it contacts the edges of the tube, and dips lowest in the middle. The curved surface formed by a liquid in a cylinder or tube is called a meniscus.
Why are cohesive and adhesive forces important for life? They play a role in many water-based processes in biology, including the movement of water to the tops of trees and the drainage of tears from tear ducts in the corners of your eyes1 . A simple example of cohesion in action comes from the water strider (below), an insect that relies on surface tension to stay afloat on the surface of water.
Glaciers are massive bodies of dense ice that are in constant motion under their own weight. In this chapter, you will learn about the formation, types, and effects of glaciers on Earth's surface and climate. You will also explore the role of glaciers in the water cycle and the impacts of climate change on glaciers. Geosciences LibreTexts is a free and open online resource for learning geology ...
Calculate the position and velocity of objects in free fall. The information presented in this section supports the following AP® learning objectives and science practices: 3.A.1.1 The student is able to express the motion of an object using narrative, mathematical, or graphical representations. (S.P. 1.5, 2.1, 2.2)
Polar Bears on Thin Ice. Polar bears live in one of the world’s harshest environments: the Arctic. Roaming across sea ice, polar bears peer through cracks in the ice to look for ringed seals, their favorite food, in the water below. Almost all of a polar bear’s food comes from the sea, and includes seals, fish, and even beluga whales.
Mar 31, 2017 · The new research found that today, nearly 30 percent of the sea ice is thin enough for sub-ice phytoplankton blooms. In fact, the Arctic sea ice has thinned by about 3 feet (1 meter) over the last ...
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Oct 19, 2023 · noun. natural or man-made lake. sublimation. noun. the process by which snow or ice becomes water vapor without first melting and passing through the liquid phase. Deglaciation is the melting of glaciers or a decrease in ice sheets. While deglaciation helped mark the end of the last ice age, glacial retreat in the 21st century helps support the ...
