What do physical and human geography have in common?

I was asked this question in my Cambridge interview and I think it is a useful starting point to encourage students to articulate why they want to study combined 'Geography', as offered at Oxbridge, rather than natural sciences or politics/sociology.
A nuanced answer demonstrates that the student has careful considered why they want to study the subject as a whole. It is not a problem if the student has already decided whether they prefer one side, but having an awareness of the broad themes underlying Geography as a discipline is key. Answers may reference 'buzzwords' such as space/scale/environment which connect the two sides of the 'physical'/'human' dichotomy; however, must be able to expand to talk in more depth about these terms. For example, what unique questions can Geography answer that other subjects may not? The answer here lies in the phrase: 'Geography is the most science of the arts, and the most arts of the science'. It acts as a necessary bridge, asking questions which 'pure' arts or science do not ask.
I would ask the student to think of a case study where both physical and human geographical understanding have been applied, and why it is effective. An example of my own would be from recently reading about conflicts between stakeholders working on active Indonesian volcanoes. From a physical perspective, understanding how the volcano works and when it is likely to erupt is crucial to saving lives. However, this information alone cannot be used to reduce casualties of eruptions in some communities due to cultural beliefs. In societies which believe that Shaman gods control the eruptions, they may be unwilling to evacuate on the advice of scientists. A holistic 'geographical' approach to such an issue must therefore involve both human and physical evaluations of the societies concerned.