AP BIOLOGY

Detailed explanation-1: -This happens to a lot of scientists! One reason that this happens is because of a property of water called cohesion. Cohesion is when two molecules that are similar to each other stick together. Water molecules are the same, and so they stick together and help keep drops on top of the penny.

Detailed explanation-2: -Gravity flattens the droplets, cohesion holds the droplets together, and adhesion holds the drops on the surface of the coin. The cohesive force is the pull of the water molecules on themselves. Each successive drop sticks to the water that’s already on the coin. We often call this cohesive force “surface tension”.

Detailed explanation-3: -Cohesion makes a water drop a drop For water, this state happens when a water molecule is surrounded on all sides by other water molecules, which creates a sphere or ball (perfectly round if it was in outer space). On Earth, the effect of gravity flattens this ideal sphere into the drop shape we see.

Detailed explanation-4: -What allows us to get such a large dome of water on top of the penny? Water has a high surface tension. This happens because water molecules like to stick together. This property is called cohesion.

Detailed explanation-5: -When plain water is dropped on a penny, water molecules strongly attract one another and the resulting surface tension is high. This is observed by the bubble-like shape formed by the water as more drops are added to the penny’s surface.