How would you determine the acceleration from a v vs. t graph?

The acceleration is the slope of the v/t graph.

-- If the graph is a straight line, then pick any piece of the line, or even the whole graph, and divide (change in 'y') by (change in 'x') for the piece you chose.

-- If the graph is a curve or a squiggle, then you can do the same thing with a piece of it, and you get the average acceleration during that piece.

-- If you need the acceleration at one point on the graph, you have to lay a straight line against that point on the graph, and find the slope of that straight line.

neither accurate nor precise.

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