A particle has initial (t = 0) velocity $\stackrel{\to <!--\; \to \; -->}{\mathrm{\mu <!--\; \mu \; -->}}=5\stackrel{^<!--\; ^\; -->}{i}$ and is at origin at this instant. Its acceleration is given by $(3\stackrel{^<!--\; ^\; -->}{i}+4\stackrel{^<!--\; ^\; -->}{j}).$ When particle’s x co-ordinate is 16 units, then its speed is