A stone of mass 1 kg is tied to a string 2 m long and it's rotated at constant speed of $40 \mathrm{~ms}^{-1}$ in a vertical circle. The ratio of the tension at the top and the bottom is [Take $g=10 \mathrm{~ms}^{-2}$]

2. Two coils have a mutual inductance of 0.01 H . The current in the first coil changes according to equation, $I=5 \sin 200 \pi t$. The maximum value of emf induced in the second coil is

The radius of the earth and the radius of orbit around the sun are 6371 km and $149 \times 10^6 \mathrm{~km}$ respectively. The order of magnitude of the diameter of the orbit is greater than that of earth by

Two open pipes of different lengths and same diameter in which the air column vibrates with fundamental frequencies ' $n_1$ ', and ' $n_2$ ' respectively. When both pipes are joined to form a single pipe, its fundamental frequency will be