Answer:
There was a change in temperature on the surface you were walking on. It is possible that "you" were walking on cool, wet sand and when your parents said it was time to leave, you ran barefoot towards the parking lot (away from the sand) and got a burning coal sensation on your feet.
Explanation:
Answer: A
Explanation:
heat always passes from a warmer object to a cooler object until all objects are the same temperature. Conduction is how heat travels between objects that are touching. Conduction travels fastest through solids, but liquids and gases can also conduct heat.
Slime flows like a liquid, but unlike familiar liquids (e.g., oil, water), its ability to flow, or viscosity, is not constant. So it's a fluid, but not a regular liquid. Scientists call a material that changes viscosity a non-Newtonian fluid. The technical explanation is that slime is a fluid that changes its ability to resist deformation according to shear or tensile stress.
What this means is, when you pour slime or let it ooze through your fingers, it has a low viscosity and flows like a thick liquid. When you squeeze a non-Newtonian slime, like oobleck, or pound it with your fist, it feels hard, like a wet solid. This is because applying stress squeezes the particles in the slime together, making it hard for them to slide against each other.
Most types of slime are also examples of polymers. Polymers are molecules made by linking together chains of subunits.
The specifics of how a type of slime works depends on its chemical composition, but the basic explanation is that chemicals are mixed to form polymers. The polymers act as a net, with molecules sliding against each other.
Two solutions are combined to make classic slime. One is diluted school glue, or polyvinyl alcohol in water. The other solution is borax (Na2B4O7.10H2O) in water.
Borax dissolves in water into sodium ions, Na+, and tetraborate ions.
The tetraborate ions react with water to produce the OH- ion and boric acid:
B4O72-(aq) + 7 H2O <—> 4 H3BO3(aq) + 2 OH-(aq)
Boric acid reacts with water to form borate ions:
H3BO3(aq) + 2 H2O <— > B(OH)4-(aq) + H3O+(aq)
Hydrogen bonds form between the borate ion and the OH groups of the polyvinyl alcohol molecules from the glue, linking them together to form a new polymer: slime.
A drought is a period of drier-than-normal conditions that results in water-related problems.<span> When rainfall is less than normal for several weeks, months, or years, the flow of streams and rivers declines, water levels in lakes and reservoirs fall, and the depth to water in wells increases.</span>
