a closed system consisting of an elastic membrane enclosing a colloidal suspension is squeezed. the compressive pressure is 10 Pa and the the volume of the system changes from 100L to 80L. during this process 1J of heat is released. calculate the change in internal energy of the system.
The work done on the system should be the pressure times the change in volume. Convert 20 liters to cubic meters so it will be in SI units. (20 L)/(1000 L/m?) 0.02 m? Work (10 Pa)(0.02 m?) [remember that a pascal is a newton/m?] 0.2 Newton meters {or Joules} So 0.2 Joule entered the system through pressure and change in volume, but 1 Joule left the system as heat, so the net change is: decrease by 0.8 Joule
how can we know 1 joule left the system? explain please. tq
