The amount of tears in the room (denoted by t) can be defined as a function of the number of people present in the room (denoted by P), the number of chopped onions in the room (denoted by O), and the deliciousness of the onions (denoted by D) using this formula:

t=3⋅P⋅O^3D^2

Select an appropriate measurement unit for amount of tears in a room.