The 12 Mg helicopter is hovering over a lake as the suspended bucket collects 5 m3 of water used to extinguish a fire. Determine the power required by the engine to hold the filled water bucket over the lake. The horizontal blade has a diameter of 14 m. Use rhow = 1000 kg/m3 and rhoa = 1.23 kg/m3

7 MW

Explanation:

mass of helicopter, m = 12 Mg = 12000  

volume of water in bucket, V = 5 m³

diameter of blade, D = 14 m

density of water, d = 1000 kg/m³

density of air, d' = 1.23 kg/m³

The weight of water and the helicopter is balanced by the thrust produced by the rotor blade of the helicopter.

So, force

F = m x g  + V x d x g

F = 12000 x 9.8 + 5 x 1000 x 9.8

F = 166600 N

Let initially the velocity of blade is v

v = 41.96 m/

Power of the helicopter, P = Force x velocity

P = 166600 x 41.96

P = 7 x 10^6 Watt

P = 7 MW

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

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