6. A rocket burning its onboard fuel while moving through space has velocity −→v (t) and mass m(t) at time t. If the exhaust gases escape with velocity −→v e, relative to the rocket, then md−→v /dt = dm/dt−→v e. (a) Show using this equation that −→v (t) = −→v (0) − ln(m(0)/m(t))−→v e; (b) If the rocket accelerates in a straight line from rest to twice the speed of its exhaust gases, then what fraction of its initial mass would the rocket have to burn as fuel?

i don't understand. explain it clearly

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