An iron sphere of mass $20 \times 10^{-3} \ kg$ falls through a viscous liquid with terminal velocity $0.5 \ ms^{-1}$. The terminal velocity (in $ms^{-1}$) of another iron sphere of mass $54 \times 10^{-2} \ kg$ is (in $.5$)

Which of the following is the simplest amino acid?

Two charges $+3.2 \times 10^{-19} \, C$ and $-3.2 \times 10^{-19} \, C$ kept $2.4 \, \mathring{A}$ apart form a dipole. If it is placed in a uniform electric field of intensity $4 \times 10^5 \, V/m$,what will be its potential energy in stable equilibrium?

Curie temperature is the temperature above which :

Let $I$ be the moment of inertia of a uniform square plate about an axis $AB$ passing through its center and parallel to two of its sides. $CD$ is an axis in the plane of the square and passing through the center,making an angle $\theta$ with $AB$. The moment of inertia of the plate about the axis $CD$ is:

$A$ neutron moving with velocity $u$ collides elastically with an atom of mass number $A$. If the collision is head-on and the initial kinetic energy of the neutron is $E$,then the final kinetic energy of the neutron after the collision is