A Styrofoam ball of radius 47 cm falls with a terminal velocity of 8.1 m/s. What is the mass of the ball? I have no idea how to really set this up or solve it. CAn someone help

it's not provided. "A Styrofoam ball of radius 47 cm falls with a terminal velocity of 8.1 m/s. What is the mass of the ball?" is all that the question gives us. I copied and pasted it from my homework