A father pushes his child in a cart. The cart starts to move. Scientists can use many physical quantities to describe what is happening.

The car is placed on a ramp, which is 20 meters high. The mass of the car and the child is 100kg.

Calculate the potential energy the car will have before it is let go and the velocity the car will travel at down the ramp assuming no frictional forces.

Acceleration due to gravity (g) = 10 m/s2

i would think it's food chain

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