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Units and Measurement

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Physics Part I

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Physics

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12
The length, breadth and thickness of a rectangular sheet of metal are 4.234 m, 1.005 m, and 2.01 cm respectively. Give the area and volume of the sheet to correct significant figures.

Given, 

Length, l = 4.234 m 

Breadth,b = 1.005 m 

Thickness, t = 2.01 cm = 2.01 × 10-2 m

Area of the sheet = 2 (l × 0 + b × t + t × l)

                       = 2 (4.234 × 1.005 + 1.005 × 0.0201 + 0.0201 × 4.234)

                       = 2 (4.3604739)

                       = 8.7209478 m2

Area can contain a maximum of three significant digits, therefore, rounding off, we get

Area = 8.72 m2

Also, volume = l × b × t

               V = 4.234 × 1.005 × 0.0201

                  = 0.0855289

                  = 0.0855 m3 (Significant Figures = 3)

 


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Define unit.

The quantity used as a standard of measurement is called unit. 

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Define physical quantity.

 


A measurable quantity in terms of which laws of Physics can be expressed is called physical quantity.

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