You place a 3.0-m-long board symmetrically across a 0.5-m-wide chair to seat three physics students at a party at your house. if 65-kg dan sits on the left end of the board and 50-kg tahreen on the right end of the board, where should 54-kg komila sit to keep the board stable? ignore the mass of the board and treat each student as point-like objects. the positive x-direction is to the right, and the origin is at the center of the chair.

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