A four-cylinder gasoline engine has an efficiency of 0.21 and delivers 180 J of

Question

A four-cylinder gasoline engine has an efficiency of 0.21 and delivers 180 J of work per cycle per cylinder. The engine fires at 25 cycles per second.

Part A

Determine the work done per second.

Express your answer to two significant figures and include the appropriate units.

Part B

What is the total heat input per second from the gasoline?

Express your answer to two significant figures and include the appropriate units.

Part C

If the energy content of gasoline is 130 MJ per gallon, how long does one gallon last?

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

(A) Work done per second = Work per cycle per cylinder* No. of cylinder * (cycle per second)
   = (180 J/cycle per cylinder)*4(cylinder)*(25 cycles/ second) = 18000 J/second
(B) We know
efficiency = Work / heat input
Heat input = 18000/0.21 = 85714.285 J/s
(C)
We know that the 85714.285 J energy is provided in 1 second
therefore 1 J energy is provided in 1/85714.285 seconds
and 130 MJ energy will be provided in = 130*106 /85714.285 seconds
Time to consume 130 MJ energy = 1516.67 seconds
We also know that 1 gallon releases 130 MJ energy , therefore
1 gallon gasoline will be consumed in 1516.67 seconds

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