Atmospheric pressure at sea level is approximately:
A. 10³ Pa
B. 10⁷ Pa
C. 10⁵ Pa
D. 10² Pa
Answer: Option C
Solution (By JKSSB Mock Tests)
Standard atmospheric pressure at sea level is 101,325 Pa, approximately 10⁵ Pa (or 1 bar, 760 mm Hg). This value is crucial for pressure calculations in fluids, thermodynamics, and meteorology. Option B (1000 Pa) is too low (about 1% of atmospheric), C and D are orders of magnitude off. Memory tip: 'Atmospheric pressure ≈ 10⁵ Pa = 100 kPa = 1 bar'. This factual knowledge is frequently tested in competitive exams as a baseline for pressure-related problems. Always use SI units (Pascal) unless specified otherwise.
Explanation:
The gravitational potential V inside a uniform solid sphere at a distance r from the center is V = -GM * (3R^2 - r^2) / (2R^3). At the exact center of the Earth, r = 0. Substituting r = 0 gives V = -GM(3R^2) / 2R^3 = -3GM / 2R. The potential is strictly non-zero and highly negative.
Explanation:
Rules: leading zeros not significant; trailing zero after decimal is significant. Digits 4,0,5,0 are significant ⇒ 4 sig figs. Memory tip: 'Start at first non-zero; include trailing zeros after decimal'. Measurement precision concept frequently tested in competitive exams.
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