- #1

lha08

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## Homework Statement

The two headlights of a car require a total of 10 A supplied at 12 V. Given that the combustion of 1 L of gasoline releases 3X 10^7 J and that the conversion to electrical power has an efficiency of 25%, how much gasoline is consumed in one hour for this purpose alone?

## Homework Equations

**3. The Attempt at a Solution [/b**

I'm not sure if what I did is right since I don't have the answers..but here I go:

-I first found the power by multiplying I X V...10 A X 12 V =120 W

-then I multiplied 120 W by 3600 seconds (an hour) to turn the answer into Joules...in this case 432000 Joules.

-Then I multiplied this by 0.25 to get 108 000 Joules.

-After this, I set a ratio with 1 L and 3X10^7 Joules with 108000 Joules and the unknown amount of gas. And I got 0.0036 L...

Is how I did it correct (i'm not really sure about the 25% part and the ratio part at the end...)

I'm not sure if what I did is right since I don't have the answers..but here I go:

-I first found the power by multiplying I X V...10 A X 12 V =120 W

-then I multiplied 120 W by 3600 seconds (an hour) to turn the answer into Joules...in this case 432000 Joules.

-Then I multiplied this by 0.25 to get 108 000 Joules.

-After this, I set a ratio with 1 L and 3X10^7 Joules with 108000 Joules and the unknown amount of gas. And I got 0.0036 L...

Is how I did it correct (i'm not really sure about the 25% part and the ratio part at the end...)