A $2\mathrm{.}5-$N force is applied to the plunger of a hypodermic needle. The diameter of the plunger is $1\mathrm{.}1$ cm and that of the needle is $0\mathrm{.}20$ mm$.$ With what force does the fluid leave the needle? What force on the plunger would be needed to push fluid into a vein where the gauge pressure is $75$ mmmm$-$HgHg$?$ Answer for the instant just before the fluid starts to move.