Mechanical model of a gas: Vibrating balls strike piston on OHP.

Mechanical Model of a Gas: in a cylinder fitted with a piston. The Apparatus is a simple mechanical model to represent gas molecules in a cylinder colliding with a moveable piston. Variable power supply simulates changing temperature in the cylinder. Adiabatic Compression of a Gas: Piston is moved from A to B, decreasing volume from V to V . Power Supply setting remains constant, but activity of steel balls increases. Volume decreases, pressure increases, temperature rises. Adiabatic Expansion of a Gas: Piston is moved from B to A, increasing volume from V to V . Power Supply setting remains constant; activity of steel balls decreases. Volume increases, pressure decreases, temperature falls. Heating a Gas at Constant Volume: Piston is held at B; volume V is constant. Power Supply setting is increased, and activity of steel balls increases. Volume is constant, temperature rises,pressure increases. Heating a Gas at Constant Pressure: Piston is moved from B to A; volume is increased from V to V . Power Supply setting is increased to produce same activity of the balls at the new position. Volume increases,temperature increases, pressure is constant. Note: Same set-up as A+35+30 & C+55+10