A student measures the length of a pencil as 7.50 cm. The number of significant figures is
A. 4
B. 3
C. 2
D. 1
Answer: Option B
Solution (By JKSSB Mock Tests)
7.50 has three significant figures (7,5,0). Trailing zero after decimal is significant. If it were 7.5 cm, two significant figures. Precision indicated by decimal places.
Explanation:
Pressure = Force/Area. Force = mass × acceleration, dimensions [MLT⁻²]. Area = L². So pressure = [MLT⁻²]/[L²] = [ML⁻¹T⁻²]. This is also the dimension of stress. Common exam trap: confuse with energy density which is also [ML⁻¹T⁻²].
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