One of the mysteries of comet studies is why new comets, arriving straight from the oort cloud, show tails even when they are a very long way from the sun - beyond the orbit of saturn? comets are thought to be dirty snowballs - mixtures of ice and rock. comet tails are thought to be caused by water ice evaporating, and carrying away tiny grains of rock, which reflect the sunlight and produce the tails we see.
but how can a comet be warm enough to melt ice when still beyond the orbit of saturn? calculate the temperature of a comet surface when it is 10 astronomical units from the sun. an astronomical unit is 1.5× , the luminosity of the sun is 3.84× and the stefan-boltzmann constant =5.67×10−8w m−2 k−4 .

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

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

conservation of mass

mass before something happens = mass afterwards