A science teacher ran a marathon. After the race she showed her students the silver blanket she was given to keep her warm. A group of students investigated how the colour of the blanket affected how much infrared radiation is absorbed

In summary the blanket that is metallic reflects electromagnetic waves

Explanation:

The teacher running the marathon generates a quantity of heat that the body must release to keep its temperature constant, one of the ways to release this energy in the form of electromagnetic radiation in the infrared range.

The matte with is silver should be metallic, so it reflects light at all wavelengths, so that the infrared light returns to the body and decreases the radiation radiation emitted, thus keeping it warmer.

In summary the blanket that is metallic reflects electromagnetic waves

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it