William was swimming at a speed of 3 m/s when he started to slow down. He slowed to a stop in 2 seconds. What is his acceleration?

on average.

Explanation:

The acceleration of an object is the rate of change in its velocity. The average acceleration of an object is equal to the change in velocity over the time required for that change to take place.

For the William in this question:

Had William not came to a complete stop, it would be necessary to consider whether there is a change to his orientation. However, because in this question William came to a stop, the change in his velocity would be:

.

That change in velocity happened over . Therefore, the average acceleration would be:

.

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