A crate is lifted vertically 1.5 m and then held at rest. The crate has weight 100 N (i. e., it is supported by an upward force of 100 N). How much work was done in lifting the crate from the ground to its final position? 1. 150 J 2. More than 150 J 3. None of these 4. A bit less than 150 J 5. No work was doneNow suppose the crate is lifted so rapidly that air resistance was significant during the raising. How much work was done by the lifting force as the box was raised 1.5 m?1. None of these 2. No work was done. 3. More than 150 J 4. Still 150 J 5. A bit less than 150 J because the air partially supported the crate.

nah.   i'm just sleepy.

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

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