Describe how atmospheric pressure changes with altitude and explain why this occurs Explain your answer using Pressure in liquids (physics only) and pressure difference.

Atmospheric pressure decreases with altitude because there are fewer air particles above a surface as height increases. This reduction in air particles leads to a decrease in the weight of the air above, resulting in lower pressure.

A strong answer should address (Physics only) Explain why pressure differences in a liquid produce an upwards force on submerged objects directly. Use the context of Pressure in liquids (physics only) within Pressure and pressure differences in fluids (physics only), then state the relevant forces or motion reasoning with units where needed. The answer is correct when it names the key physics quantity, keeps force and pressure distinct, and links the conclusion back to the approved learning objective.