David tied a ball to the end of a long string. Holding the end of the string, he swung the ball in a circle around him to model how Earth orbits the sun. He knows that the orbit of Earth depends upon the gravitational pull. Which component of David’s model illustrates the effect of gravity?

A) The ball

B) The string

C) The distance from David

D) The speed the ball revolves

compass can be used day and night, cloudy or sunny

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

im srry but ur wrong the answer is d a smooth rock, some red dirt, and an empty bird's nest.