$P, Q$ and $R$ are long parallel straight wires in air, carrying currents as shown. The direction of the resultant force on $R$ is:

$A$ projectile is fired from the surface of the earth with a velocity of $5\, ms^{-1}$ at an angle $\theta$ with the horizontal. Another projectile fired from another planet with a velocity of $3\, ms^{-1}$ at the same angle follows a trajectory which is identical to the trajectory of the projectile fired from the earth. The value of the acceleration due to gravity on the planet is (in $ms^{-2}$) (given $g = 9.8\, ms^{-2}$):

$\begin{aligned} & \frac{x^2+x+1}{(x-1)(x-2)(x-3)}=\frac{A}{x-1}+\frac{B}{x-2}+\frac{C}{x-3} \\ & \Rightarrow A+C= \end{aligned}$

Compound squamous epithelium is found in

The moment of inertia of a uniform semicircular disc of mass $M$ and radius $r$ about a line perpendicular to the plane of the disc passing through its center is:

The technique used to make numerous copies of a specific segment of $DNA$ quickly and accurately is