Help me An atomic nucleus suddenly bursts apart (fission) into two pieces. Piece A with mass mA travels to the left with a speed of vA. Piece B with mass mB travels to the right with speed vB. Show the velocity of piece B in terms of mA, mB and VA.

Solution:

Consider that the nucleus is not acted by an external force. Thus, momentum is conserved, so: pBf + pAf = 0

Substituting the expression for momentum results to

mBv (_) + (_) mAv (_) = 0

Deriving the expression for the velocity of piece B results to

v(_) =(mA/m _)vA

Explanation:

We can apply the law of conservation of momentum on the nucleus in its initial and final state of nucleus:

Initial Momentum = Final Momentum

momentum of nucleus before bursting = momentum of piece A + momentum of Piece B

since, nucleus was initially at rest. Therefore,

velocity of nucleus = 0 m/s

and due to opposite direction of forces:

Vb = - Vb

Therefore,

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

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.