Two wires of same length and radius are joined end to end and loaded. The Young's modulii of the materials of the two wires are Y₁ and Y₂. The combination behaves as a single wire then its Young's modulus is :

The half-life of $${}^{198}Au$$ is 3 days. If atomic weight of $${}^{198}Au$$ is 198 g/mol then the activity of 2 mg of $${}^{198}Au$$ is [in disintegration/second] :

Two billiard balls of equal mass 30g strike a rigid wall with same speed of 108 kmph (as shown) but at different angles. If the balls get reflected with the same speed then the ratio of the magnitude of impulses imparted to ball 'a' and ball 'b' by the wall along 'X' direction is :

In the Young's double slit experiment, the distance between the slits varies in time as
d(t) = d₀ + a₀ sin$$\omega$$t; where d₀, $$\omega$$ and a₀ are constants. The difference between the largest fringe width and the smallest fringe width obtained over time is given as :