Solve for $$y$$ if $${{{d^2}y} \over {d{t^2}}} + 2{{dy} \over {dt}} + y = 0$$ with $$y(0)=1$$ and $${y^1}\left( 0 \right) = - 2$$

For the following matrix $$\left[ {\matrix{ 1 & { - 1} \cr 2 & 3 \cr } } \right]$$ the number of positive characteristic roots is

The composition of an oxy-acetylene flame for cutting of steel contain more oxygen.

In an orthogonal cutting operation,
The depth of cut $$=2$$ $$mm,$$
Width of cut $$=15$$ $$mm,$$
Cutting speed $$=0.5$$ $$m/s$$ and
The rake angle $$=0$$ deg.
The cutting force and the thrust force are respectively $$900$$ $$N$$ and $$600$$ $$N$$ and the shear angle $$=30$$ $$deg$$.

The average coefficient of friction between the chip and the tool is