The engine in a small airplane is specified to have a torque of 500 n⋅m . this engine drives a 2.4- m -long, 40 kg single-blade propeller. on startup, how long does it take the propeller to reach 2000 rpm ?

8.04 second

Explanation:

torque = 500 Nm

Length of blade, L = 2.4 m

mass of blade, m  40 kg

initial angular velocity, ωo = 0  rad/s

frequency, f = 2000 rpm = 2000 / 60 rps

final angular velocity, ωf = 2 x π x 2000 / 60 = 209.33 rad/s

Moment of inertia of the blade,

I = 19.2 kg m^2

Torque = Moment of inertia x angular acceleration

500 = 19.2 x α

where, α be the angular acceleration

α = 26.04 rad/s^2

Use first equation of motion

ω = ωo + αt

where t is the time taken by the propeller to reach 2000 rpm.

209.33 = 0 + 26.04 x t

t = 8.04 second

Thus, the time taken by the propeller is 8.04 second.

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