Answer to Question 4

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Equation:

The angular velocity:

w = 2 pf = 2 p 50 Hz = 314.15 rad s-1

 

We know the mass per unit length:

m = 1.25 10-3 kg 1.60 m = 7.8125 10-4 kg m-1

 

(a) Now we can work out the power:

P = 1/2 7.8125 10-4 kg m-1 (2 p 50.0 Hz)2 (20 10-3 m)2 115 m s-2 = 1.77 W = 1.8 W (2 s.f.)

 

(b) I = (1.77 W 2.5 V) = 0.71 A (2 s.f.)