Amine elevator cage with a mass of 2.5 tons empty is descending at a rate of 32 km/hr when the hoist mechanism jams and stops suddenly. if the cable is steel with a cross-sectional area of 6.5 cm2 and the cage is 1500 meters below the hoisting drum when the drum jams, which of the following most nearly equals the stress in the cable? (e for hoist cable equals 84,000 x 106 pa, neglect the weight of the cable)

σ = 4.1 MPa

Explanation:

Given that

m= 2.5 kg

v=  32 km.hr

v= 8.88 m/s

The kinetic energy of the mass ,KE

KE = mv²/2

KE = 2.5 x 8.88²/2

KE= 98.56 J    -------1

The strain energy of the string

----2

KE= E

σ = 4.1 MPa

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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