Amodel of a helicopter rotor has four blades, each of length 3.80 m from the central shaft to the blade tip. the model is rotated in a wind tunnel at a rotational speed of 450 rev/min. a. what is the linear speed of the blade tip? b. what is the radial acceleration of the blade tip expressed as a multiple of the acceleration of gravity?

a)V= 179.056 m/s

b)

Explanation:

Given that

Length of blade = 3.8 m

Rotational speed N= 450 rev/min

We know that

  ω=47.12 rad/s

Linear velocity

We know that linear velocity V =  ω x r

Here r = 3.8 m

So by putting the values

V =  ω x r

V = 47.12  x 3.8 m/s

V= 179.056 m/s

Radial acceleration  

dang that balls went far

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