# Uncertainty in Measurement, S.I Units, Precision and Accuracy and Significant Figures

Derived S.I units :

(i) Area = length × length
= meter × meter = meter2 = m2

(ii) Volume = length × breadth × height
= m × m × m  =  m3

(iii) Speed = distance / time = meter / sec = ms−1

(iv) \tt Acceleration = \frac{Change \ in \ velocity \ (m \ sec^{-1})}{Time \ \left(sec\right)}

(v) Force = mass (kg) × acceleration (m  sec−2)
= kg ms−2 = newton (N)

(vi) \tt Pressure = \frac{force \left(kg \ m \ sec^{-2}\right)}{Area \ \left(m^{2}\right)}
kg m−1 s−2 = pascal (pa)

Scientific notation :
0.0000187 = 1.87 × 10−5
120789 = 1.20789 × 105
N1 = N × 10n
n = exponent (+ve or −ve and is integer)
N = any suitable number (usually between 1 to 9)

### Part2: View the Topic in this Video from 0:20 to 9:39

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1. Precision = Individual value − arithmetic mean value

2. Accuracy = Mean value − true value

3. °F = \tt\frac{9}{5}(°C) + 32

4. K = °C + 273.15