-
Like us on facebook euclideacademyzambia
ACKNOWLEDGEMENT
Special thanks to the following: My Parents(D.Kalenga, S.Mumba), siblings and
the entire family for the inspiration. Ezekiel.C.Daka,
EUCLIDE ACADEMY PUBLICATIONS
Copyright c 2018 by Evans Mumba
All rights reserved. This book or any portion thereof may not be reproduced or
used in any manner whatsoever without the express written permission of the
publisher except for the use of brief quotations in a book review.
——————————
Contents
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2
Units of Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3
Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1
Measuring Instruments
11
3.2
Period of a pendulum
13
1. Introduction
Physics is the study of the world around us. In a sense we are more qualified
to do physics than any other science. From the day we are born we study the
things around us in an effort to understand how they work and relate to each other.
Learning how to catch or throw a ball is a physics undertaking for example.
Mathematical Skills
You should be comfortable with scientific notation and how to write scientific
notation. You should also be able to easily convert between different units and
change the subject of a formula. In addition, concepts such as rate, direct and
indirect proportion, fractions and ratios and the use of constants in equations are
important.
Rounding off
Giving the complete number for something is sometimes unnecessary. For instance,
the attendance at a football match might be 23745. But for most people who want
to know the attendance figure, an answer of ’nearly 24000’, or ’roughly 23700’,
is fine.
We can round off large numbers like these to the nearest thousand, nearest
hundred, nearest ten, nearest whole number, or any other specified number.
Round 23745 to the nearest thousand.
1. First, look at the digit in the thousands place. It is 3. This means the number
lies between 23000 and 24000.
Chapter 1. Introduction
6
2. Look at the digit to the right of the 3. It is 7. That means 23745 is closer to
24000 than 23000.
3. Remember
4. The rule is, if the next digit is: 5 or more, we ’round up’. 4 or less, it
stays as it is.
23745 to the nearest thousand = 24000.
23745 to the nearest hundred = 23700.
Scientific Notation
Standard form, or standard index form, is a system of writing numbers which
can be particularly useful for working with very large or very small numbers. It is
based on using powers of 10 to express how big or small a number is.
Standard form is written in the form of Equation: a × 10n , where
a is a number bigger than or equal to 1 and less than 10.
n can be any positive or negative whole number. For example Equation: 3.1 × 1012
Scientists use standard form when working with the speed of light and distances
between galaxies, which can be enormous. The size of bacteria or atoms may also
be referred to in standard form as they are so tiny. Standard form is also sometimes
referred to as scientific notation.
Significant Figures
In a number, each non-zero digit is a significant figure. Zeroes are only counted
if they are between two non-zero digits or are at the end of the decimal part.
For example, the number 2000 has 1 significant figure (the 2), but 2000,0 has 5
significant figures. You estimate a number like this by removing significant figures
from the number (starting from the right) until you have the desired number of
significant figures, rounding as you go. For example 6,827 has 4 significant figures,
but if you wish to write it to 3 significant figures it would mean removing the 7
and rounding up, so it would be 6,83.
Physical Quantity
A physical quantity is anything that you can measure. For example, length,
temperature,distance and time are physical quantities.
enjoying the sample?
get yourself the full
Amazing physics book
find us on
facebook euclidezambia
0971514960
2. Units of Measurements
Measurement means comparing any physical quantity with a standard to determine
its relationship to standard. This standard is called unit. All measurable quantity
expressed in: (1) some number or magnitude and
(2) some unit
For example if the distance is 200km, 200 is the number or magnitude and km
(kilometer) is the unit.
Units are important for two main reasons (a) They help us avoid mistakes when
calculating (b) they help us validate our answers after calculations
Measurement of physical quantities - base units
Length or distance (s) The base unit of length or distance is meter (m). The
measurement of length is used to calculate the:
thickness of a thin wire using vernier calliper.
(The precision of length measurements can be
increased by using the devices that use sliding
vernier scale.)
area of square or rectangle = length(x) and
width(y)
1
area of triangle = base × height
2
volume of cube = length × width × height as
well as volume of liquid = height in calibrated
measuring cylinder
Chapter 2. Units of Measurements
8
Mass (m)
How to change units
It is very important that you are aware that different systems of units exist. Furthermore, you must be able to convert between units. Being able to change between
units (for example, converting from millimetres to metres) If you want to change
Figure 2.1: Diagram
millimetre to metre, you divide by 1000 (follow the arrow from mm to m); or if
you want to change kilometre to millimetre, you multiply by 1000 × 1000. The
same method can be used to change millilitre to litre or kilolitre.
Figure 2.2: Diagram
Example:
Express 4 900 mm in metres.
Answer:
1. Use Figure 2.2. Millimetre is on the left and metre in the middle.
2. You need to go from mm to m, so you are moving from left to right.
3. 4900 mm ÷1000 = 4.9 m. cool right..!
Conversion 2
Convert 12.86 kg to g.
enjoying the sample?
get yourself the full
Amazing physics book
find us on
facebook euclidezambia
0971514960
9
Answer:
1. use figure 2.3
2. You need to go from kg to g, so it is from right to left.
3. 12.86 × 1000 = 1286g
Extra Conversions
Converting speed
When converting km/h to m/s you multiply by 1 000 and divide by 3 600
1000m
3600s
For example convert 72 km/h to m/s
72 × 1000 = 7200 ÷ 3600 = 20m/s
When converting m/s to km/h, you multiply by 3 600 and divide by 1 000.(
3600s
1000m )
For example 30 m/s
30 × 3600 ÷ 1000 = 108km/h
Converting temperature
Converting between the Kelvin and Celsius temperature scales is simple. To
convert from Celsius to Kelvin add 273. To convert from Kelvin to Celsius
subtract 273.
Kelvin temperature=Celsius temperature + 273
Task
1. Write down the SI unit for the each of the following quantities
(a) length
(b) time
(c) mass
2. For each of the following units, write down the symbol and what power of
10 it represents
(a) millimetre
(b) centimetre
(c) metre
(d) kilometre
3. Write each of the following in scientific notation, correct to 2 decimal
places:
(a) 0,00000123 N
(b) 417 000 000 kg
(c) 246800 A
(d) 0,00088 mm
4. The Concorde is a type of aeroplane that flies very fast. The top speed of
the Concorde is 844 km/hr Convert the Concorde’s top speed to m/s
5. The boiling point of water is 100◦ C. What is the boiling point of water in
kelvin?
enjoying the sample?
get yourself the full
Amazing physics book
find us on
facebook euclidezambia
0971514960
3. Measurements
3.1
Measuring Instruments
Measuring instruments and their uses
Measuring rule
A rule, is an instrument used in geometry, technical drawing and building to
measure distances and/or to rule straight lines.
Uses:
Rule can be used to measure lengths of different objects.
Vernier Callipers The labeled parts are
Figure 3.1: Diagram
1. Outside large jaws: used to measure external diameter or width of an object
2. Inside small jaws: used to measure internal diameter of an object
3. Depth probe/rod: used to measure depths of an object or a hole
Using the calliper
1. Read the main scale where it lines up with the sliding scale’s zero.So here
you are reading only the main scale.The main scale on a Vernier calliper
typically tells you the whole number plus the first decimal
For Example figure 3.2 shows a vernier calliper
Chapter 3. Measurements
12
Figure 3.2: Using the calliper
2. The reading on the main scale before the zero mark of the movable scale
here is 13.0 cm
3. Read the Vernier scale. Find the first mark on the Vernier scale that lines up
perfectly with any line on the main scale (we have a total of 21 divisions,
each division is 0.02 so our number is 21 × 0.02 = 0.42). That mark tells
you the value of the additional digits ( i.e ’0.’ zero point) so what ever you
read add (’0.’zero point ) to the first i.e 0.42 mm
4. Add the numbers together i.e on the main scale plus the vernier scale
13.0mm + 0.42mm = 13.42mm
Engineers Callipers
The inside callipers are used to measure the internal size of an object Outside
callipers are used to measure the external size of an object.
(a) 1
(b) 2
Figure 3.3: Engineers Callipers
Micrometer screw gauge
A micro mete screw gauge is used to make smaller measurements or dimensions
e.g thickness of paper, diameter of a needle etc. A micrometer reading contains
two parts:
• the first part is contributed by the main scale on the sleeve
• the second part is contributed by the rotating vernier scale on the thimble
To obtain the first part of the measurement:
enjoying the sample?
get yourself the full
Amazing physics book
find us on
facebook euclidezambia
0971514960
3.2 Period of a pendulum
13
1. Look at figure 3.4, you will see a number 2.5 to the immediate left of the
thimble. This means 2.5 mm. (Notice that there is an extra line below the
line on 2, this represents an additional 0.5 mm.)
2. To obtain the second part of the measurement: Look at the image above, the
number 38 on the rotating vernier scale coincides with the datum line on the
sleeve. Hence, 0.38 mm is the second part of the measurement
3. You just have to add the first part and second part of the measurement to
obtain the micrometer reading: 2.5 + 0.38 = 2.88 mm.
Time
It is the ordering or duration of events. The unit of time is second (s). The common
devices to measure the time or duration of an event are clock and stopwatch.
The precession of time duration of an event can be improved by measuring the time
for number of events and dividing time by total number of events. For example to
measure the time period of a pendulum the time for ten swings should be recorded
and dividing the total time by ten to get the time for one swing.
Pendulum
Figure 3.4: Diagram
A simple pendulum consists of a point mass suspended at the end of a cord of
zero mass. A close approximation to this is a small metal mass on a long, light
string or thread The time for one complete swing is the period (i.e from A to B
and back to A)
3.2
Period of a pendulum
the Period of a pendulum is the time taken for one complete swing or oscillation
determined by the formula. where t is time, n the number of swings
P=
t
n
enjoying the sample?
get yourself the full
Amazing physics book
find us on
facebook euclidezambia
0971514960