During boiling, temperature remains constant because heat is used to:
A. Increase kinetic energy
B. Expand volume
C. Increase pressure
D. Break intermolecular bonds
Answer: Option D
Solution (By JKSSB Mock Tests)
At boiling point, supplied heat (latent heat) breaks intermolecular bonds for phase change, not increasing kinetic energy (temperature). Potential energy increases while kinetic energy (temperature) stays constant. Memory aid: 'Latent heat changes state, not temperature'. Conceptual question testing phase change understanding, common in competitive exams to assess microscopic interpretation.
Explanation:
T = 2π√(R/g) ≈ 5076 s ≈ 84.6 min for r ≈ Earth radius. Standard result. Memory aid: 'Low orbit: ~84 min; geostationary: 24 hours'. Orbital mechanics fact frequently tested in competitive exams.
Explanation:
Acceleration a = dv/dt ⇒ dv = a·dt. Integrating: ∫dv = ∫a·dt ⇒ Δv = area under a-t graph. Slope of v-t gives acceleration; area under a-t gives velocity change. Memory aid: 'a-t graph area = Δv; v-t graph area = displacement'. Graph interpretation skill essential for motion analysis in competitive exams.
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