Question

a)The price of 1KWh of electricity is 10.43cents ($0.10). Considering a gallon of gas ($2.45) contains about 36 kilowatt hours of energy (1.3x10^8 J/gallon), determine which is a more expensive source of energy.

b) what is the change in internal energy of a car if you put 12 gallons of gasoline into its tank? (assume that all factors, such as temperature, are constant).

Answer 1

Ans:-

A] 1KWh electricity is $(0.10)≈Rs 7

Gallon of gas is 36KWh $(2.45)≈Rs 169

Now for 1KWh for gallon gas 36 = 169

                                                          1 =    ?

1KWh = Rs4.69 ≈5

So electricity is more expansive

B] Using the energy content of a gallon of gasoline 1.3* 10^8 J/gal , the energy stored in 12.0 gallons of gasoline is:

Egas =(1.3 *10 ^8J/gal)(12.0 gal) =1.6 *10^9 J.

Therefore, the internal energy of the car increases by this energy, so that∆ U= 1.6 *10^9 J.