These coins were made a few years before my mom was born. The 1972 are made of a copper-zinc-nickel alloy and the 1975 are an iron or steel alloy. I’ll show with a magnet for fun.
Those 5 piso coins should be Nickel, and nickel is magnetic. https://en.numista.com/catalogue/pieces4518.html
Actually these 3 ferromagnetic elements: iron, cobalt, and nickel (including gadolinium but it is a lanthanide) arent magnetic in small concentrations in alloys. Thats why the 1972 1 piso coins werent magnetic
In fact most of the philipino currency made in 2010 and post 2010 are magnetic Because it was cheaper to make because it’s steel.
the Philippines was a English colony until 1967 and the currency was “peso”. After 1967 it changed from peso to piso because they were not an english pr american colony anymore, also i forgot to tell you guys this when @serafino and @Inspector43 asked the questions
"Peso" might have been a holdover from the Spanish colony era in the Philippines. I have a crown sized silver Philippine's 1897 one Peso coin that was minted by the Spanish.