Learn Finnish: Minua pelottaa, joten pudottaudun maahan. - I am scared, so I drop to the ground.

It is built from the transitive verb pudottaa (to drop something). By attaching the reflexive suffix -utua, it becomes pudottautua, meaning to drop oneself or to let oneself fall. When you conjugate it for the first person, the final t in the suffix weakens to d, giving us pudottaudun.

Why do we use the partitive minua pelottaa instead of minä pelkään?

While both mean being scared, pelottaa is an experiencer verb. It forces the person feeling the emotion into the partitive case (minua) and keeps the verb in the third-person singular (pelottaa). It feels more like the emotion is happening to you (it frightens me) rather than you actively performing the fear as a standard subject.

Why does the double tt in pudottaudun stay strong, but the final t changes to d?

Consonant gradation only happens when a syllable becomes closed. In the stem pudottautu-, the syllable after the double tt is open, so the tt remains strong. However, adding the first-person marker -n closes the very last syllable, which forces the single t in the -utu- suffix to weaken into a d.

Why does the word for ground (maa) take the illative case ()?