The number of protons in an atom determines its MCQ with Answer and Explanation

Explanation:
Constant velocity implies zero acceleration, net force = 0 by Newton's first law. Engine force balances friction and air resistance. Net force zero, not necessarily zero forces.

Explanation:
Gauge pressure (excluding atmospheric) P_gauge = ρgh ∝ h. Doubling depth doubles gauge pressure. Total pressure P = P₀ + ρgh increases but not exactly double due to P₀ term. Question asks about pressure increase (ρgh part). Memory tip: 'Hydrostatic pressure ∝ depth'. Fundamental fluid statics concept frequently tested in competitive exams.

Explanation:
Law of reflection: angle of incidence = angle of reflection, both measured from normal. So 30°. If angle with mirror is given, convert to normal. Always equal for smooth surfaces.