The human eye is like a camera that has a lens with :

A uniform meter scale of mass 0.24 kg is made of steel. It is kept on two wedges, W₁ and W₂, in a horizontal position. W₁ is at a distance of 0.2 m from one of its ends, while W₂ is at a distance of 0.4 m from the other end. If the force on the scale is N₁ due to W₁ and N₂ due to W₂, then : (take g = 10.0 m s⁻²)

Escape speed from the Earth is close to 11.2 km s⁻¹. On another planet whose radius is half of the Earth's radius and whose mass density is four times that of the Earth, the escape speed in km s⁻¹ will be close to :

Which one of the following does not apply to sound waves in fluids?