If a gas expands, is the work done positive, negative, or zero?

The first law of thermodynamics then reduces to

dQ = dW + dU ⇒ dU = −dW (1)

where dW is the amount of work done by the gas and dU is the change in internal energy.

Since the gas is expanding, the work being done by the gas is positive. Eqn. (1) then implies that the change in internal energy of the system must be negative, that is, the internal energy

is decreasing. The only true statements are then:

• The work done by the gas is positive, and no heat exchange occurs.

• The internal energy of the system decreases.

the boundarys like convergent divergent and transform it causes subduction

the answer is solomon northrup. he was a free-born african american, abolitionist and professional violinist that was drugged, kidnapped and sold as slave in 1841 and remained in captivity until 1853 where he regained his freedom with the of the then-governor of new york, washington hunt. he wrote and published his memoirs "twelve years a slave" in 1853, and in this text, he tells the story of his escape thru one of louisiana's swamps (the great pacoudrie swamp) in which he ended up covered in green slime from crossing the surface of the dead water.