Quick question about 1-D kinematics.

Ok I really don't want the answer for this problem but on a homework assignment I received a problem that went like this.

A rock, released at rest from the top of a tower, hits the ground after 1.5 s. What is the speed of the rock as it hits the ground? (g = 9.8 m/s² and air resistance is negligible)

I know that the initial velocity is 0 m/s, the time is 1.5 s and the amount of mass is 9.8 m/s^2.

The problem I'm having with this question is out of all the formulas given for 1D Kinematics I don't see one that involves the mass. I know that I should convert the grams to kilograms because of the S.I unit but I do not know how to plug in the mass to the equations I have been given. Could someone help a junior in high school taking Physics out?