Which phrase describes air pressure?
A. decreases with denser air B. decreases as altitude decreases C. equals mass divided by volume D. decreases as a result of fewer air particles pushing down
The Correct Answer and Explanation is :
The correct answer is D. decreases as a result of fewer air particles pushing down.
Explanation:
Air pressure is defined as the force exerted by the weight of air above a given point. It is influenced by several factors, including altitude, temperature, and the density of the air. As altitude increases, the amount of air above a point decreases, resulting in fewer air particles pushing down. This phenomenon explains why air pressure is lower at higher elevations.
At sea level, there is a substantial column of air above us, which exerts a higher pressure due to the combined weight of all the air molecules. However, as one ascends in elevation—such as climbing a mountain or flying in an airplane—there are fewer air molecules above the observer, which leads to a decrease in air pressure. This drop in pressure can also be observed in weather patterns; for instance, low-pressure systems are often associated with stormy weather because they indicate that there are fewer air particles in that area.
Moreover, air pressure is directly related to the density of air. Denser air (which contains more air molecules in a given volume) exerts more pressure than less dense air. However, the key factor regarding altitude and air pressure is the number of air molecules present. As altitude increases, the density of air decreases, which corresponds with fewer air molecules exerting downward force.
In summary, the correct phrase describing air pressure is D. decreases as a result of fewer air particles pushing down. This highlights the crucial relationship between altitude and air pressure, illustrating how the weight of air diminishes as one moves higher above sea level, leading to the physiological effects often experienced by climbers and aviators.