1. an astronaut with a mass of 77.5kg is stuck in space floating 15.0m away from his ship.
his motion relative to the ship is 0 m/s. fortunately, he is holding a 2.0kg wrench. he throws
the wrench in the opposite direction of the ship at 12m/s. what is the wrench's change in
momentum?

24 kg m/s

Explanation:

The change in momentum of the wrench is given by:

where

is its final momentum

is its initial momentum

At the beginning, the wrench is at rest together with the astronaut, so its momentum is zero:

After it is launched, its momentum becomes

where

m = 2.0 kg is its mass

v = 12 m/s is its velocity (taking the direction of the wrench motion as positive)

Substituting,

So, the wrench's change in momentum is

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