A dimensionless constant $K$ in a physics equation is defined as $K = \frac{P \cdot t}{\rho \cdot v^2}$, where $P$ is pressure ($\text{kg}/(\text{m} \cdot \text{s}^2)$), $t$ is time ($\text{s}$), $\rho$ is density ($\text{kg}/\text{m}^3$), and $v$ is velocity ($\text{m/s}$). What are the SI units of $K$?