3. Hot air _ and cold air _ due to _
• falls; rises; gravity
O rises; falls; gravity
O rises,; falls; bouyancy
• falls; rises; boyancy
• warms; cools; convection
The correct answer is:
- Hot air rises and cold air falls due to buoyancy
The correct answer is: "Hot air rises and cold air falls due to buoyancy."
To understand why hot air rises and cold air falls, we need to consider the concept of buoyancy. Buoyancy refers to the upward force exerted on an object immersed in a fluid (in this case, air). In general, a fluid exerts greater pressure on the bottom of an object compared to the top. This pressure difference creates an upward force on the object, causing it to float or rise.
When it comes to air, temperature plays a significant role. Hot air is less dense than cold air because the molecules in hot air have higher energy and are more spread out. On the other hand, cold air is denser because the molecules have lower energy and are more tightly packed together.
Due to this difference in density, hot air has a lower average mass per unit volume compared to cold air. As a result, hot air is buoyant and tends to rise while cold air is less buoyant and tends to sink.
Gravity also plays a role in this process. Gravity pulls all objects, including air, towards the Earth's surface. However, the buoyancy force is stronger for hot air, so hot air overcomes the force of gravity and rises upwards. Conversely, cold air, being less buoyant, is unable to overcome gravity's pull and falls towards the Earth's surface.
In summary, hot air rises and cold air falls due to the buoyancy force caused by the difference in density between the two air masses.