Figure below shows a liquid being pushed out of the tube by a piston having area of cross section 2.0 $\mathrm{cm}^2$. The area of cross section at the outlet is $10 \mathrm{~mm}^2$. If the piston is pushed at a speed of $4 \mathrm{~cm} \mathrm{~s}^{-1}$, the speed of outgoing fluid is $\_\_\_\_$ $\mathrm{cm} \mathrm{s}^{-1}$.