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?

200 J

800 J

1,300 J

1,700 J

The final answer is 1,700 J

Explanation: According to first law of thermodynamics:

=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=  {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

U2- 1500J= + 500J --300J

U2= 1700J

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.