The least count of a screw gauge is 0.001 cm. The reading of a measurement is 0.250 cm. How many significant figures does it have? MCQ with Answer and Explanation
The least count of a screw gauge is 0.001 cm. The reading of a measurement is 0.250 cm. How many significant figures does it have?
A. 3
B. 1
C. 4
D. 2
Answer: Option A
Solution (By JKExamLibrary)
Reading 0.250 cm has three significant figures (2,5, and trailing zero after decimal). Least count gives precision, trailing zero indicates measurement to 0.001 cm, so it's significant.
Explanation:
Pressure has dimensions [ML⁻¹T⁻²]. Energy per unit volume: Energy is [ML²T⁻²], volume is [L³], so [ML²T⁻²]/[L³] = [ML⁻¹T⁻²], matching pressure. Force per unit length is [MLT⁻²]/[L] = [MT⁻²]. Momentum per unit area is [MLT⁻¹]/[L²] = [ML⁻¹T⁻¹]. Power per unit volume is [ML²T⁻³]/[L³] = [ML⁻¹T⁻³]. This dimensional equivalence explains why pressure appears in Bernoulli's equation alongside energy density. Memory aid: Pressure and energy density both represent stored energy per spatial dimension.
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