QUANTITY AND MEASUREMENT Abdul malik sr Live on malikdul87@gmail.com

Physical Quantity A quantity which can be measured is called a physical quantity. (e.g. velocity, mass, length, force, weight, time, etc) The quantity which can not be measured is not physical quantity. (e.g., funny, love, feeling, taste, happiness, afraid, collision, sadness etc) Conclusion, Physical quantity is something which can be measured and it has a unit.

Measurement Measuring is to Compare a physical quantity of an object with a unit of measurement to get the value.

UNIT In the past, people used parts of their body as units of measurement such as cubit, fathoms, span and step. Those units are not standard and can cause difficulty in communicating them. In 1960 the metric system was used and officially called the international system or SI Units ( La Systeme International d’Unites)

For measuring more or less than one meter you can use prefixes in the table below. Symbol Multiplying Factor Kilo k 1000 103 Hecto h 100 102 Deca da 10 101 Deci d 0.1 10-1 Centi c 0.01 10-2 Mili m 0.001 10-3 Micro µ 0.000001 10-6 Nano n 0.000000001 10-9

Unit Conversion km hm dam m dm mm : 10 x 10 cm

EXERCISES Convert the following readings to the units indicated and then write down to factors of ten: 1. 0.5 m = ………………… km o.5 m =…………. cm 2. 150 g = ………………… kg 150 g = ………….. mg 3. 0.25 s = ……………….. ms 4. 2 m2 = ……………….. mm2 5. 500 mL = ………….. L 6. 0.2 m3 = ……….. cm3

Write down seven fundamental quantities on your notebook Physical quantities divided into: Fundamental quantities Derived quantities 1.Fundamental Quantities Fundamental quantities are quantities which conventionally established by International conference on weight and measurement. Write down seven fundamental quantities on your notebook

The seven fundamental quantities are shown in the table below: SI Unit Symbol Length meter m Mass kilogram kg Time second s Electric current Ampere A Temperature Kelvin K Amount of subtance mol Luminous Intensity candela cd

2. Derived quantities Derived quantities are quantities which are derived from the fundamental quantities Example: The physical quantity of velocity is derived from Fundamental quantities namely length and time. The formula is given: where S = distance (length) (m) t = time (s) v = velocity (m/s) S v = t Base quantities are said to have base units and derived quantities have derived units. For example, if displacement and time are chosen to be base quantities, then velocity is a derived quantity:

Explain, what is the meaning of fundamental quantities? EXERCISE Explain, what is the meaning of fundamental quantities? Mention 3 examples of fundamental quantities and its units on SI. Explain, what is the meaning of derived quantities? Mention 3 examples of derived quantities and its units. Mention quantities are arrange derived quantities below: Area Volume Density

SOME EXAMPLES OF DERIVED SI UNITS Physical Quantity SI Unit Symbol area square meter m2 volume cubic meter m3 density kilogram per cubic meter kg.m-3 speed meter per second m.s-1 acceleration meter per second squared m.s-2 concentration mole per cubic meter mol.m-3

Length Length is represents the distance between two point SI unit of length: meter - The meter is the distance travelled by light in a vacuum during a time interval of 1/299 792 458 of a second.

Estimate the length of your bench. Measuring Length Estimate the length of your bench. Then check your answer using a meter rule, measuring tape or ruler My estimate : Length = …………………….. cm Using a ruler/meter rule/ measuring tape: Length =……………………… cm

Conclusion My estimate of length………….. (Is/ is not) accurate We use ……………………… to measure length accurately

Measurement of Length To measure length, we can use rulers, meter rule, a measuring tape, a vernier caliper and a micrometer screw gauge. Measuring tape Ruler The measuring tape and meter rule are use to measure length accurately to 0.1 cm Vernier calipers Vernier calipers has an accuracy of 0.01 cm Micrometer screw gauge Micrometer screw gauge has an accuracy of 0.001 cm

Some instruments used for measuring length Length to be measured Smallest unit of measurement Measuring tape Several meters 0.1 cm (or 1 mm) Meter rule Several centimeters to 1 meter 0.1 cm ( or 1 mm) Vernier calipers Several millimeters to centimeters 0.01 cm (or 0.1 mm) Micrometer screw gauge Less than 1 millimeter to about 2 centimeter 0.001 cm (or 0.001mm)

The correct way to read the scale on a ruler is shown in figure below. Parallax error is due to incorrect positioning of your eye when you take measurements. In order to prevent parallax error, your eyes must be perpendicular to the scale

Measure the length, width and thickness of your textbook. Length = ………….cm Width = .…………cm Thickness = …………… cm Length Width Thickness Science Text Book 2. Using a measuring tape to measure the circumference of a beaker. Circumference of the beaker =………….. cm

Let us find the thickness of a sheet of paper in your textbook.   Number of sheets in the textbook =……… Total Thickness of all the sheets = ……… cm     Note: Do not include the covers. Why not? Conclusion: Thickness of one sheet = ……………..cm

Vernier calipers

Vernier Calipers Inside Jaws Depth Gauge Screw Clamp Main Scale Outside Jaws Depth Gauge Vernier Scale Main Scale Screw Clamp 4/4/2019

How do you read the measurement on a pair of vernier calipers? Read the main scale marking just before the zero marking of the vernier scale. This show 4.7 cm Find the vernier scale marking which is in line with the main scale marking. This show 0.4 mm Result = 4.7cm + 0.4 mm = 4.7 cm + 0.04 cm = 4.74cm 4/4/2019

Checking for zero error Positive zero error If the zero marking of the vernier scale is to the right of the zero marking on the main scale Negative zero error - If the zero marking of the vernier scale is on the left of the zero marking on the main scale 4/4/2019

EXERCISE 1. ……………………shows the distance between two points. 2. The SI unit for length is…………………………. 3. Look at the figure below ! Write the length pointed by the arrows in the figure! a…… mm =……cm f. ……mm =……cm b. ……mm =……cm g. ……mm =……cm c. ……mm =……cm h. ……mm =……cm d. ……mm =……cm i . ……mm =……cm e …… mm =…….cm j. ……mm =……cm

Micrometer screw gauge

Parts of Micrometer screw Gauge

How do you read the measurement on a micrometer screw gauge? 1. Read the marking on the sleeve just before the thimble. 2. Find the thimble scale marking which is in line with the main scale.

What is the difference between mass and weight? The amount of materials in the substance is called mass The SI unit of mass, the kilogram (kg), is defined as the mass of a specific platinum–iridium alloy cylinder kept at the International Bureau of Weights and Measures at Sèvres, France What is the difference between mass and weight?

A spring weighing scale No Mass Weight 1. Mass an object is fixed, although the object’s position changes Weight an object is not fixed if the object’s position change 2. Mass is not affected by the gravitational force Weight is affected by the gravitational force 3. In SI, mass uses basic unit kilogram In SI, Weight uses unit is Newton 4. The mass of an object is measured with lever balance The weight is measured with spring balance 5. Mass is amount of substance of an object Weight is the force gravitational an object A spring weighing scale

Instrument to measure mass Beam balance Electrical balance

Time Time is the duration between two events The SI unit for time is second. One standard second is the time needed by Cesium atom to vibrate 9,192,631,770 times The nation’s primary time standard is a cesium fountain atomic clock developed at the National Institute of Standards and Technology laboratories in Boulder, Colorado.

Time Conversion 1 day = 24 hours 1 hour = 60 minutes 1 minute = 60 seconds For fast event, you can use milisecond (ms), microsecond (µs) and nanosecond (ns)

Temperature Degree of hotness of an object. The SI unit for temperature is Kelvin The common measuring tool for temperature is thermometer People know degree Celcius (°C), Fahrenheit (°F) and Kelvin (K) as the scale on thermometer

Temperature Conversion TK = Tc + 273

Derived Quantity : Volume and Area A. Volume Volume shows the space occupied by an object The unit of volume is m3 Liter is not the SI unit, but frequently used in our life. 1 dm3 = 1 L

MEASUREMENT OF VOLUME DO YOU KNOW, WHAT IS IT ? It is a measuring Cylinder 10 30 50 70 It is a measuring Cylinder scale scale

NOW, LOOK AT THIS stone 10 30 50 70 70 50 30 10 Initial water level (V0) is 30 ml

stone 10 30 50 70 70 50 30 10 Initial water level (V0) is 30 ml

Thus, the volume of rock is The formula used to measure the volume of an irregular shaped object is V = V1 – V0 NOTE : V = volume of irregular shaped object V0 = The initial water level V1 = The final water level 10 30 50 70 stone Thus, the volume of rock is 50 mL – 30 mL = 20 mL 70 50 30 10 Initial water level (V0) is 30 ml Final water level ( Vt ) is 50 ml

Measuring volume of regular and irregular solid Please make a report of your activity on your exercise book Measuring volume of regular and irregular solid 1. Objective:………….. 2. Material: Cube Stone Measuring cylinder ………………. and so on 3. Procedure: Measure volume regular solid: ………………………………. ………………………………. and so on Measure volume irregular solid: ……………………………….. and so on 4. Data & Analyze: Volume of cube:……………cm3 Volume of stone: …………. mL 5. Conclusion: To measure volume of regular solid we can use….. To measure volume of irregular solid we can use….

Conclusion To measure the volume of regular solid can be determined by measuring length, width and height. To measure the volume of irregular solid can be determined by using a measuring cylinder.

What is the unit of volume? How to measure volume of regular-shaped object? Explain. How to measure volume of irregular-shaped object? Explain. What is the formula to find volume of regular-shaped? Explain. What is the formula to find the volume of irregular-shaped object? Explain.

Is the amount of space that a flat surface covers. A. AREA Is the amount of space that a flat surface covers. Area is derived quantity which is derived from fundamental quantity namely length. The SI unit of area is square metre (m2)

How to measure area of an object? For a regular shape: - can determined by measurement or calculation rectangle trapezium a b h a a width h h parallelogram b b circle length r A = height x ½ x (a+b) A = length x width heigth r r r A = πr2 A = base x height

For irregular shape Please do activity of measuring areas.

Conclusion To measure the area of regular shape can be determined by measurement or calculation To measure the of irregular shape can be determined by tracing the object on a sheet of graph paper.