Question

In a heat engine, if 500 J of heat enters the system, and the piston does 300 J of work, what is the final internal (thermal) energy of the system if the initial energy is 1,500 J?

800 J

1,300 J

200 J

1,700 J

Answer 1

1700 J

Step-by-step explanation:

Answer 2

Answer: The final energy is 1,700 J

Explanation: According to first law of thermodynamics:

`\Delta U=q+w`

`\Delta U=U_2-U_1`=Final energy-initial energy=Change in internal energy

q = heat absorbed or released

w = work done by or on the system

w = work done by the system=
`-P\Delta V` {Work done by the system is negative as the final volume is greater than initial volume}

q = +500J {Heat absorbed by the system is positive}

w = work done by the system = -300J

`U_2-1500J=+500J-300J`

`U_2=1700J`