Assertion : A spring of force constant $k$ is cut into two pieces having lengths in the ratio 1 : 2. The force constant of series combination of the two parts is $$\frac{3 k}{2}$$.
Reason : The spring connected in series are represented by $$k=k_1+k_2$$
Assertion : The total kinetic energy of a rolling solid sphere is the sum of translational and rotational kinetic energies.
Reason : For all solid bodies, total kinetic energy is always twice of translational kinetic energy.
Assertion : In He-Ne laser, population inversion takes place between energy levels of neon atoms.
Reason : Helium atoms have a metastable energy level.
Assertion : It is hotter over the top of a fire than at the same distance on the sides.
Reason : In the upward direction, the heat propagate through convection.