4. An automobile gasoline engine is able to do 225 J of useful work with each stroke of its

pistons. If the engine has an efficiency of 29%, what is the amount of work that must be done on

the pistons in the engine?

pistons. If the engine has an efficiency of 29%, what is the amount of work that must be done on

the pistons in the engine?

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Actually Welcome to the concept of Efficiency.

We know that, efficiency is given as,

E (eta) = Output work / Input Work

hence, here, E = 29% and Output work = 225

hence, 29% = 29/100 in real..

hence, the work done on piston is given as,

29/100 = 225/I

therefore, I = 225*100/29 ==> I = 22500/29 ==> I = 775.8 joules

hence, the work done on the pistons is 775 J