Chapter 1:
Motion, forces and energy
Physics (0625)
,Physical quantities and measurement
techniques
Units and basic quantities
Length (L) is measured with metres (m)
Mass (m) is measured with kilograms (Kg)
Time (t) is measured with seconds (s)
Powers of ten
5000 = 5x10x10x10 = 5x103
500 = 5x10x10 = 5x102
50 = 5x10 = 5x101
5 = 5x1 = 5x100
0.5 = 5/10 = 5x10-1
0.05 = 5/100 = 5x10-2
0.005 = 5/1000 = 5x10-3
Length
1 decimeter (dm) = 10-1 m
1 centimetre (cm) = 10-2 m
1 millimetre (mm) = 10-3 m
1 micrometre (µm) = 10-6 m
1 nanometer (nm) = 10-9 m
1 kilometre (km) = 103 m
1 gigameter (Gm) = 109 m
1
Khaled Murrar
,When measuring length using a ruler, your eye must be directly
over the mark on the scale to avoid parallax error.
Significant figures
Significant figures: the number of figures that is given for a
measurement and indicates how accurate we think it is and more
figures should not be given than justified.
When doing calculations, the answer should have the same number
of significant figures as the measurements used in the calculation.
For example, if the measurement had three significant figures and
the calculator gave the answer as “4.51245” it should be written
as “4.51”.
In standard notation, the number of significant figures is the
number of digits before the power of ten. For example, 4.52x103
has three significant figures.
2
Khaled Murrar
, Area
The SI unit of area is square metre (m2)
1 cm2 = 10-4 m2
Square or rectangle
area = length x breadth
Triangle
1
area = 2
x base x height
Circle
area = πr2
Volume
Volume is the amount of space occupied.
The SI unit of volume is metre cubed (m3)
1 cm3 = 10-6 m3
Regularly shaped objects
volume = length x breadth x height
Sphere
4
volume = 3
πr3
Cylinder
volume = πr2h
3
Khaled Murrar
Motion, forces and energy
Physics (0625)
,Physical quantities and measurement
techniques
Units and basic quantities
Length (L) is measured with metres (m)
Mass (m) is measured with kilograms (Kg)
Time (t) is measured with seconds (s)
Powers of ten
5000 = 5x10x10x10 = 5x103
500 = 5x10x10 = 5x102
50 = 5x10 = 5x101
5 = 5x1 = 5x100
0.5 = 5/10 = 5x10-1
0.05 = 5/100 = 5x10-2
0.005 = 5/1000 = 5x10-3
Length
1 decimeter (dm) = 10-1 m
1 centimetre (cm) = 10-2 m
1 millimetre (mm) = 10-3 m
1 micrometre (µm) = 10-6 m
1 nanometer (nm) = 10-9 m
1 kilometre (km) = 103 m
1 gigameter (Gm) = 109 m
1
Khaled Murrar
,When measuring length using a ruler, your eye must be directly
over the mark on the scale to avoid parallax error.
Significant figures
Significant figures: the number of figures that is given for a
measurement and indicates how accurate we think it is and more
figures should not be given than justified.
When doing calculations, the answer should have the same number
of significant figures as the measurements used in the calculation.
For example, if the measurement had three significant figures and
the calculator gave the answer as “4.51245” it should be written
as “4.51”.
In standard notation, the number of significant figures is the
number of digits before the power of ten. For example, 4.52x103
has three significant figures.
2
Khaled Murrar
, Area
The SI unit of area is square metre (m2)
1 cm2 = 10-4 m2
Square or rectangle
area = length x breadth
Triangle
1
area = 2
x base x height
Circle
area = πr2
Volume
Volume is the amount of space occupied.
The SI unit of volume is metre cubed (m3)
1 cm3 = 10-6 m3
Regularly shaped objects
volume = length x breadth x height
Sphere
4
volume = 3
πr3
Cylinder
volume = πr2h
3
Khaled Murrar
