Un satélite artificial de un planeta x tiene un periodo de 8 horas y está colocado a una distancia de 50000 km del centro del planeta. a) ¿cuál es la masa mx del plaeta? b) ¿cuál es el valor de la aceleración de la gravedad del planeta a la distancia en la que está colocado el satélite? c) ¿cuál es la velocidad orbital del satélite? d) si la masa ms del satélite es de 200 kg ¿cuál es su energía de enlace?

whichever one it is, it's definitely not one that you included on the list you provided.

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

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form