For the following digital logic circuit, the correct truth-table is

The ratio of the velocity of sound in hydrogen gas $\left(\gamma=\frac{7}{5}\right)$ to that in helium gas $\left(\gamma=\frac{5}{3}\right)$ at the same temperature is

Moment of inertia of a disc about an axis passing through its centre and perpendicular to its plane is 'I'. The ratio of moment of inertia about a parallel axis tangential to its rim to passing through a point midway between the centre and the rim is

Two cars start from a point at the same time in a straight line and their positions are represented by $x_1(t)=a t+b t^2$ and $x_2(t)=F t-t^2$. At what time do the cars have the same velocity?