“Past” can also describe movement, as in “Jeremy ran past Owen,” or take the place of the word "beyond," as in “the path to the river is past the gate.”
The word “passed,” on the other hand, means to go by. The conjugation for the verb “to pass” appears below.
She passed her brother without waving.
She ran past her brother without waving.
To muddy the waters further, “passed” can also mean to hand something off, as in “the congregation passed the plate.” Another meaning is to demonstrate knowledge of content, as in “most of the class passed the science test.”
The table below summarizes when to use “past” and “passed.”