2013-3-1 Mechanical Forms of Work Two requirements for a work interaction between a system and its surroundings to exist: -there must be a force acting on the boundary -the boundary must move. zz） When force is not constar Nork=Forcex Distanc W=F() (kJ If there is no movement no work is done© Expansion or Compression Work A月 Moving boundary work SW=pAdx SW =pdv W=「pdV Work is not a property! pv"=constant Polytropic process 2-22 112013-3-1 11 Mechanical Forms of Work Two requirements for a work interaction between a system and its surroundings to exist: – there must be a force acting on the boundary. – the boundary must move. The work done is proportional to the force applied (F) and the distance traveled (s). Work = Force × Distance When force is not constant If there is no movement, no work is done ☺ Expansion or Compression Work 2-22 2 1 d d d V V W pA x W pV W pV δ δ = = = ∫ constant n pv = Work is not a property! Moving boundary work Polytropic process