In the final section of the lab, the student is asked to investigate the energy distribution of the spring system described previously. The student pulls the mass down an additional 20.6 cm from the equilibrium point of 27.5 cm when the mass is stationary and allows the system to oscillate. Using the equilibrium point of 27.5 cm as the zero point for total potential energy, calculate the velocity and total potential energy for each displacement given and insert the correct answer.

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

there are no contact forces mentioned on the list of choices that you've provided.

answerdmitry mendeleyev made a workable classification of the elements