What is the minimum energy required to launch a satellite of mass ' $m$ ' from the surface of the earth of mass ' $M$ ' and radius ' $R$ ' at an altitude $2 R$ ?

A wire of length ' $L$ ' and area of cross section ' $A$ ' is made of material of Young's modulus ' $r$. It is stretched by an amount ' $x$ '. The work done in stretching the wire is

In a parallel plate air capacitor the distance between plates is reduced to one fourth and the space between them is filled with a dielectric medium of constant 2 . If the initial capacity of the capacitor is $4 \mu \mathrm{~F}$. then its new capacity is

An aircraft is moving with uniform velocity $150 \mathrm{~m} / \mathrm{s}$ in the space. If all the forces acting on it are balanced, then it will