The Amount of Time It Takes for an Object Bounce $T = 2 \pi \sqrt { \frac { m } { k } }$

Essay

The amount of time it takes for an object bounce up and down through one complete cycle is
called the "period" and is calculated using the following equation: $T = 2 \pi \sqrt { \frac { m } { k } }$
where
$\begin{array} { l } T = \text { period in seconds } \\m = \text { mass of object in kilograms } \\k = \text { spring rate }\end{array}$
What is the appropriate unit for $k$ if the preceding equation is to be homogeneous in units?