Write answers with significant figures:a) 17.35 g +8.498 g
1 answer:
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Answer:
581 kJ, work was done by the system
Explanation:
According to the first law of thermodynamics:
where
is the change in internal energy of the system
Q is the heat absorbed by the system (positive if absorbed, negative if released)
W is the work done by the system (positive if done by the system, negative if done by the surrounding)
In this problem,
Therefore the work done by the system is
And the positive sign means the work is done BY the system.
Initially there were 10 bulbs of 60 Watt power
So total power of all bulbs = 60 * 10 = 600 W
now each bulb used for 4 hours daily
so total energy consumed daily
now we have total power consumed in 1 year
cost of electricity = 10 cents/ kWh
so total cost of energy for one year
Now if all 60 Watt bulbs are replaced by 30 Watt bulbs
So total power of all bulbs = 30 * 10 = 300 W
now each bulb used for 4 hours daily
so total energy consumed daily
now we have total power consumed in 1 year
cost of electricity = 10 cents/ kWh
so total cost of energy for one year
total money saved in 1 year