Everything Science Grade 10

CHAPTER 1. SKILLS FOR SCIENCE 1.3

Constants in equations ESAN

A constant in an equationalwayshas the same value. For example the speed of light
(c= 2, 99 × 108 m·s−^1 ), Planck’s constant (h) and Avogadro’s number (NA) are all examples
of constants that are use in science. The following table lists all the constants that you will
encounter in this book.

Constant Symbol Value and units SI Units

Atomic mass unit u 1 , 67 × 10 −^24 g 1 , 67 × 10 −^27 kg

Charge on an electron e − 1 , 6 × 10 −^19 C − 1 , 6 × 10 −^19 s·A

Speed of sound (in air, at 25 ◦) 344 m·s−^1

Speed of light c 3 × 108 m·s−^1

Planck’s constant h 6 , 626 × 10 −^34 J·s 6 , 626 × 10 −^34 kg·m^2 s−^1

Avogadro’s number NA 6 , 022 × 1023

Gravitational acceleration g 9 , 8 m·s−^1

Trigonometry ESAO

Trigonometry is the relationship between the angles and sides of right angled triangles.
Trigonometrical relationships are ratios and therefore have no units. You should know the
following trigonometric ratios:

A

adjacent

hypotenuse

opposite

• Sine
  This is defined as sinA=hypotenuseopposite


• Cosine
  This is defined as cosA=hypotenuseadjacent

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