It is known that the 10 kg pipe will roll up the ramp and not slide on the ramp when P becomes sufficiently large. Using the rolling assumption, find the minimum P required to cause impending motion of the 10 kg pipe up the ramp. Note that the coefficients of friction for the block/ramp, the pipe/ramp and the pipe/block contacts are each 0.30.

65.73N

Explanation:

The frictional force is a force that opposes the motion of an object on a flat surface or an inclined surface.

It is always acting up an incline plane .

Since the pipe will tend to roll up the plane, then both the impending force P also known as frictional force and the moving force Fm both will be acting up the plane.

The net force acting up the plane is

Fnet = P + Fm... (1)

The force perpendicular to the plane known as the normal reaction R must be equal to the force acting along the ramp in other to keep the body in equilibrium i.e R = Fnet

If R = W = mgcos (theta)

and Fm = mgsin(theta)

Then mgcos theta = Fnet

mgcos (theta) = P+Fm

mgcos (theta) = P+mgsin(theta)

P = mgcos (theta) - mgsin(theta)... (2)

Given mass = 10kg

g = 9.81m/s

We can get theta from the formula;

µ = Ff/R = wsin theta/wcos theta

µ = sin theta/cos theta

µ = tan(theta)

0.3 = tan (theta)

theta = arctan0.3

theta = 16.7°

P = 10(9.81)cos16.7° - 10(9.81)sin16.7°

P = 98.1(cos16.7°-sin16.7°)

P = 98.1(0.67)

P = 65.73N

The minimum force P required to cause impending motion is 65.73N

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

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.