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2.9 if an industrial battery can turn a motor/machinery fixture for 8 hours and

ID: 2268157 • Letter: 2

Question

2.9 if an industrial battery can turn a motor/machinery fixture for 8 hours and the motor is rated at 2hp, how much energy is stored in the battery in J? In kwh 1 hp= 746 w

2.11 a house contains five 60w, two 75w and three 40w lightbulbs. If electricity costs $.12/kwh, and the lights are on for 9 hours per night, determine (a) amount of energy used per night in kwh and (b) the total cost per night.

2.22 Assuming a source voltage of 0.8v, determine the current in a 50 mw led.

2.35 what is the current flow through a 12.5kohm resistor if 3.0MV are applied?

2.43 if the voltage drop across a lighting circuit is 120v, what is the power dissipated if the lights have an operating resistance of 144 ohms?

2.46If a copper wire has a diameter of 4.54 mm and a length of 38.5 m, what is its resistance at room tempature?

Explanation / Answer

(2.9)

Motor rating is,  

P=2hp

= 2*746

=1492 W

Calculate the energy.

w= pt

=1492*8

=11936

=11.936 kwh

It is known that,

1kwh= 3600000 J

Therefore,

w= 11.936*3600000

=42.969*10^6 J