The Magic of Convection Currents: A Lesson in Thermodynamics and Gas Laws
What happens when two identical balloons filled with helium are placed in different temperature environments and released from a height of 1 meter?
A. The balloons both rise. The cold balloon is larger than the warm balloon.
B. The balloons rise at the same rate. Both balloons are the same size.
C. The warm balloon expands and rises. The cold balloon shrinks and sinks.
D. The cold balloon expands and rises. The warm balloon shrinks and sinks.
The Most Likely Observation:
The correct answer is option C, that is, the warm balloon expands and rises, and the cold balloon shrinks and sinks.
It is known from the ideal gas equation, that PV = nRT. Here, P is pressure, V is volume, n is the number of atoms in gas, R is gas constant, and T is temperature. From the equation, it is clear that the volume of the balloon is directly proportional to the temperature.
It signifies that at constant pressure when the temperature elevates, the volume of the balloon will increase and when the temperature reduces, the volume of the balloon will decrease. Thus, the volume of the warm balloon will increase because of which its density increases and it can rise easily as a less dense substance can easily rise in air in comparison to a more dense gas or substance. Therefore, the cold balloon shrinks and sinks.