If the angular velocity of earth's spin is increased such that the bodies at the equator start floating, the duration of the day would be approximately : [Take g = 10 ms^$$-$$2, the radius of earth, R = 6400 $$\times$$ 10³ m, Take $$\pi$$ = 3.14]

An object of mass m₁ collides with another object of mass m₂, which is at rest. After the collision the objects move with equal speeds in opposite direction. The ratio of the masses m₂ : m₁ is :

In a series LCR circuit, the inductive reactance (X_L) is 10$$\Omega$$ and the capacitive reactance (X_C) is 4$$\Omega$$. The resistance (R) in the circuit is 6$$\Omega$$. The power factor of the circuit is :

A particle of mass m moves in a circular orbit under the central potential field, $$U(r) = - {C \over r}$$, where C is a positive constant. The correct radius $$-$$ velocity graph of the particle's motion is :