A 2 kg mass moving at 4 m/s collides elastically with a stationary 2 kg mass. After collision, first mass MCQ with Answer and Explanation

Explanation:
Myopia (nearsightedness) requires diverging lens (concave). Hypermetropia needs convex.

Explanation:
Hydrometer measures relative density. Lactometer for milk, but general is hydrometer.

Explanation:
Torque τ = r × F, so dimensions [L][MLT⁻²] = [ML²T⁻²]. Work W = F·d, dimensions [MLT⁻²][L] = [ML²T⁻²], identical. Momentum is [MLT⁻¹], force [MLT⁻²], power [ML²T⁻³]. Though torque and work have same dimensions, they are physically distinct: torque is vector (rotational effect), work is scalar (energy transfer). Memory tip: 'Torque and work share [ML²T⁻²]; but torque = rF sinθ, work = Fd cosθ'. This dimensional analysis question tests ability to compare quantities, frequently appearing in competitive exams. Always verify dimensions but remember physical context differs.