A12.0-kg package in a mail-sorting room slides 2.00 m down a chute that is inclined at 53.0° below the horizontal. the coefficient of kinetic friction between the package and the chute’s surface is 0.40. calculate the work done on the package by (a) friction, (b) gravity, and (c) the normal force. (d) what is the net work done on the package

Answer

given,

mass of the package = 12 kg

slides down distance = 2 m

angle of inclination = 53.0°

coefficient of kinetic friction = 0.4

a) work done on the package by friction is

              W_f = -μk R d

                   = -μk (mg cos 53°)(2.0)

                   =-(0.4)(8.0 )(9.8)(cos 53°)(2.0)

                   = -37.75 J

b)

work done on the package by gravity is

             W_g = m (g sin 53°) d

                   = (8.0 )(9.8 )(sin 53°)(2.0 )

                   =125.23 J

c)

the work done on the package by the normal force is

             W_n = 0

d)

the net work done on the package is

           W = -37.75 + 125.23 + 0

           W = 87.84 J

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