Which measuring instrument is most suitable for measuring the internal diameter of a narrow tube with high precision?
A. Meter scale
B. Vernier caliper
C. Measuring tape
D. Screw gauge
Answer: Option B
Solution (By JKExamLibrary)
Vernier caliper is ideal for measuring internal diameters of narrow tubes due to its internal jaws designed for such measurements. Screw gauge measures external dimensions like wire diameter. Meter scale and measuring tape lack the precision (least count ~1 mm) needed for narrow tubes. Vernier calipers typically have least count 0.01 mm or 0.02 mm. Practical tip: Always use internal jaws for internal measurements, external jaws for outer dimensions. This application-based question tests knowledge of instrument selection in experimental physics, commonly featured in practical examination sections.
Explanation:
At highest point velocity is zero, but acceleration due to gravity is still g (9.8 m/s²) downward. This causes it to fall back. Acceleration constant throughout free fall.
Explanation:
From Newton's law: F = Gm₁m₂/r² ⇒ G = Fr²/(m₁m₂). Force F has [MLT⁻²], r² has [L²], m₁m₂ has [M²]. Thus G = [MLT⁻²][L²]/[M²] = [M⁻¹L³T⁻²]. Memory aid: 'G dimensions: [M⁻¹L³T⁻²]; small value (6.67×10⁻¹¹) reflects weak gravity'. This dimensional analysis question tests ability to derive constants, frequently appearing in competitive exams. Always verify by substituting into fundamental equations; dimensional consistency is a powerful tool for error checking in physics problems.
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