A particle having charge $10^{-9}$ C moving in $x$-$y$ plane in fields of $0.4 \hat{j}$ N/C and $4 \times 10^{-3} \hat{k}$ T experiences a force of $(4 \hat{i} + 2 \hat{j}) \times 10^{-10}$ N. The velocity of the particle at that instant is _________ m/s.

If X and Y are the inputs, the given circuit works as _________.

If a body of mass 1 kg falls on the earth from infinity, it attains velocity (v) and kinetic energy (k) on reaching the surface of earth. The values of v and k respectively are __________.

(Take radius of earth to be 6400 km and g = 9.8 m/s²)

In a screw gauge the zero of main scale reference line coincides with the fifth division of the circular scale when two studs are in contact. There are 100 divisions in circular scale and pitch of screw gauge is 0.1 mm. When diameter of a sphere is measured, the reading of main scale is 5 mm and 50^th division of circular scale coincides with the reference line of main scale. The diameter of sphere is ______ mm.