ðə kɹaɪtˈiəɹɪən fɔːɹ pˈɜːfɛktli sˈɜːkjʊlɚ mˈoʊʃən æɾɚ ɹˈeɪdɪəs ˈɑːɹ zˈiəɹoʊ ɪz ðætðə fˈɜːst tˈɜːm ɔnðə lˈɛft biː zˈiəɹoʊ:
The criterion for perfectly circular motion at a radius r0 is that the first term on the left be zero: