Uniform acceleration: v-t graph is: MCQ with Answer and Explanation

Explanation:
The height of capillary rise is given by Jurin's law: h = 2Tcos(theta) / (rrhog). In a freely falling elevator, the effective acceleration due to gravity (g') is zero (weightlessness). As effective g approaches zero, the theoretical height h approaches infinity. In reality, the water will rise to the very top of the tube, regardless of its length, but will not overflow.

Explanation:
Photoelectric effect requires photon energy hν ≥ work function φ of metal. Thus frequency ν must exceed threshold ν₀ = φ/h, regardless of intensity. Intensity affects number of electrons, not emission possibility. Memory aid: 'Photoelectric: frequency threshold (quantum effect); intensity affects current, not emission'. This quantum physics concept is frequently tested in competitive exams. Always distinguish classical wave prediction (intensity-dependent) from quantum reality (frequency-dependent); this was key evidence for photons.

Explanation:
KE lost = ½ m v² = ½×0.01×90000 = 450 J. Work = F×s => 450 = F×0.1 => F = 4500 N.