Question

The gas in a gas-filled balloon is used in balloon flights is heated to (1) increase the kinetic energy of the gas (2) decrease the density of the gas (3) increase the density of the gas (4) give a comfortable feeling to the balloonist at cold altitudes

Short answer

Decrease the density of the gas (2).

Step-by-step solution

Identify the Purpose of Heating the Gas

Recognize that heating the gas in a balloon impacts its physical properties. This step will help determine which option correctly aligns with the known effects of heating gases.

Analyze Kinetic Energy

Heat increases the temperature, which raises the kinetic energy of the gas particles, making them move faster. This aligns with option (1).

Evaluate Density Changes

Heating a gas typically reduces its density. This decreased density is crucial because it allows the balloon to rise in the air. Therefore, option (2) is correct.

Dismiss Irrelevant Options

Option (3) is incorrect because heating the gas does not increase the density; instead, it decreases it. Option (4) might be a pleasant consequence, but it is not the primary reason for heating the gas.

Select the Correct Answer

Based on the analysis, the primary effect of heating the gas is to decrease its density, allowing the balloon to ascend. Thus, option (2) is the correct answer.

Key concepts

Kinetic Energy

Kinetic energy refers to the energy that particles have due to their motion. When a gas in a balloon is heated, its temperature increases. This rise in temperature boosts the kinetic energy of the gas particles. Higher kinetic energy means the particles move faster and collide more often. These rapid movements cause the gas to expand.

As the gas particles move faster and push against the balloon's walls, they take up more space. This is why heating the gas is crucial for balloon flights. The expansion of gas helps in creating lift, which is essential for the balloon to rise and stay afloat.

Understanding kinetic energy is fundamental in explaining why hot air balloons work. The increased motion of gas particles directly affects other gas properties, such as density, which we will discuss next.

Gas Density

Gas density is the measure of how much mass a gas has in a given volume. When gas in a balloon is heated, its density decreases. This happens because the gas expands and its particles spread out more, occupying larger space but with the same mass.

In the context of balloon flights, lower gas density is advantageous. A gas with lower density than the surrounding air creates buoyancy. This buoyant force helps the balloon to ascend. Less dense, hot air inside the balloon is lighter compared to the cooler, denser air outside. Hence, the balloon rises.

In simple terms, heating the gas decreases its density, making it lighter and allowing the balloon to float easily into the sky.

Temperature Effects

Temperature has a profound impact on gases. When the temperature of the gas in a balloon is raised, it leads to an increase in kinetic energy and a decrease in density. This two-fold effect is key to understanding balloon flights.

Warmer temperatures cause gas particles to move more vigorously. This movement makes the particles spread out, lowering the overall density. Additionally, the heated gas expands, which makes the balloon increase in volume.

For balloonists, adjusting the temperature is a practical way to control ascent and descent. By increasing the temperature, they can make the balloon rise quickly. Conversely, letting the air cool can cause the balloon to descend gently. Understanding these temperature effects is essential for safe and efficient balloon operation.