A balloon is filled with a gas which is lighter than air. It is observed to rise in air up to a certain height. State the reason why the balloon stops rising.
the density of air decreases with altitude
the balloon stops rising because the density of the gas inside is close to the ambient air density
the weight of the balloon itself also contributes to the loss of bouyancy
The reason why a balloon stops rising in the air is due to the concept of buoyancy. Buoyancy is the upward force exerted on an object immersed in a fluid, in this case, air.
When a balloon is filled with a gas that is lighter than air, it becomes less dense than the surrounding air. This difference in density creates an upward buoyant force on the balloon, causing it to rise.
However, as the balloon ascends higher, the surrounding air becomes less dense. The density of air decreases with an increase in altitude. As the density of the surrounding air decreases, the buoyant force acting on the balloon decreases as well.
Eventually, a point is reached where the buoyant force equals the weight of the balloon and its payload. At this point, the forces acting on the balloon are balanced, resulting in it no longer rising. This is known as the equilibrium point or the maximum height the balloon can reach.
It is also important to note that other factors, such as air resistance and the weight of the balloon, can influence its ascent and descent. However, in the case of a balloon filled with a gas lighter than air, the primary factor is the change in the surrounding air's density with altitude.