Current location - Health Road Network - Medical equipment enterprise - Hanging tower "is a common lifting equipment." The motor nameplate of a tower crane is marked with rated voltage of 38V, rated power of 38KW and coil resistance of .4Ω.

Hanging tower "is a common lifting equipment." The motor nameplate of a tower crane is marked with rated voltage of 38V, rated power of 38KW and coil resistance of .4Ω.

1) As the motor works normally, the power consumed is equal to the rated power, that is, P=38kW=3.8×14W, and the working time t=2s. Therefore, the electric energy consumed by the motor is:

w = Pt = 3.8× 14W× 2s = 7.6× 15J

(2) Current when the motor works normally:

I = = 1a

Heat generated by the coil: Q = i2rt = (1a) 2×. The total amount of electrical energy converted into mechanical energy is

W total = w-w1 = 7.6× 15j-8× 14j = 6.8× 15j

Because η = = that is, 8%=

the solution is g = 2.72× 14n

, the mass of the heavy object is: <

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