Two identical springs of constant '$$\mathrm{K}$$' are connected in series and parallel in shown in figure. A mass '$$\mathrm{M}$$' is suspended from them. The ratio of their frequencies is series to parallel combination will be

The radii of curvature of both the surfaces of a convex lens of focal length '$$\mathrm{f}$$' and focal power '$$\mathrm{P}$$' are equal. One of the surfaces is made plane by grinding. The new focal length and focal power of the lens is respectively

A photon has wavelength $$3 \mathrm{~nm}$$, then its momentum and energy respectively will be $$[\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}, \mathrm{c}=$$ velocity of light $$=3 \times 10^8 \mathrm{~m} / \mathrm{s}]$$

A stone is projected vertically upwards with velocity 'V. Another stone of same mass is projected at an angle fo $$60^{\circ}$$ with the vertical with the same speed $$(\mathrm{V})$$. The ratio of their potential energies at the highest points of their journey, is

$$\left[\sin 30^{\circ}=\cos 60^{\circ}=0.5, \cos 30^{\circ}=\sin 60^{\circ}=\frac{\sqrt{3}}{2}\right]$$