Identify the pair of physical quantities that have same dimensions:

The distance between Sun and Earth is R. The duration of year if the distance between Sun and Earth becomes 3R will be :

A stone of mass m, tied to a string is being whirled in a vertical circle with a uniform speed. The tension in the string is

Two identical charged particles each having a mass 10 g and charge 2.0 $$\times$$ 10^$$-$$7C are placed on a horizontal table with a separation of L between them such that they stay in limited equilibrium. If the coefficient of friction between each particle and the table is 0.25, find the value of L. [Use g = 10 ms^$$-$$2]