Question

If you release a helium balloon, it soars upward and eventually pops. Explain this behavior.

Short answer

A helium balloon soars upward and eventually pops due to the principles of buoyancy, lighter gaseous properties of helium, and expansion & rupture of the balloon at high altitudes. The buoyant force of the helium balloon is greater than its gravitational force, making it rise. As it rises, the atmospheric pressure decreases, causing the helium inside to expand. Eventually, the stress from the expanding helium exceeds the balloon material's strength, causing it to pop.

Step-by-step solution

Buoyancy and Archimedes' Principle

Buoyancy is the force exerted on an object partially or fully immersed in a fluid. Archimedes' Principle states that the upward buoyant force on an object is equal to the weight of the fluid displaced by the object. A helium balloon experiences buoyancy due to the difference in density between the helium gas inside the balloon and the air outside the balloon. The weight of the air displaced by the balloon is greater than the weight of the helium inside, creating an upward buoyant force.

Helium Balloon Rises

Helium is a lighter gas compared to air because of its lower density. When the balloon is filled with helium, its total weight becomes less than the weight of the air it displaces. This causes an unbalanced upward force on the balloon, which makes it rise. The buoyant force is always acting upwards, working against the downward force of gravity. As gravity cannot pull the balloon down with enough force due to its light weight, the balloon rises.

Expansion of Helium with Altitude

As the helium balloon rises, the atmospheric pressure and temperature decrease. With decreasing external pressure, the pressure of helium inside the balloon causes it to expand. At high altitudes, the helium atoms inside the balloon move faster and occupy a greater volume. The balloon material keeps expanding as the helium gas expands inside it.

Balloon Pops

The expansion of the helium gas continues as the balloon reaches higher altitudes. Eventually, the stress in the material of the balloon due to the expanding helium becomes greater than the material's strength. When the stress exceeds the breaking point of the material, the balloon pops. The point at which the balloon pops depends on various factors like the type of balloon material, the initial helium pressure, and the temperature at altitude. In summary, the behavior of a helium balloon soaring upward and eventually popping can be explained through the principles of buoyancy, lighter gaseous properties of helium, and expansion & rupture of the balloon at high altitudes.