Measurement.

Question 1

Why do we repeat experiments?

Answer 1

To make the results more accurate and reliable.

Question 2

How can we make results more reliable?

Answer 2

By repeating experiments.

Question 3

What are SI units?

Answer 3

Basic quantities have internationally recognized units, called SI units.

Question 4

Why are internationally recognized SI units good?

Answer 4

This is to enable people in different countries to have the same idea of quantity.

Question 5

What are prefixes?

Answer 5

Prefixes tell us how much bigger or smaller the number is than the base unit.

Question 6

Give the symbol, size, and example of the following prefixes:

• micro.
• milli.
• centi.
• deci.

Answer 6

Micro

• µ.
• one millionth.
• microsecond.

Milli

• m.
• one thousandth.
• millimetre.

Centi

• c.
• one hundredth.
• centimetre.

Deci

• d.
• one tenth.
• decimetre.

Question 7

Give the symbol, size, and example of the following prefixes:

• deca.
• hecto.
• kilo.
• mega.

Answer 7

Deca

• D.
• ten.
• decametre.

Hecto

• h.
• hundred.
• hectometre.

Kilo

• k.
• thousand.
• kilogram.

Mega

• m.
• million.
• megabyte.

Question 8

Name 2 sources of errors that can cause the reading to be inaccurate.

Answer 8

• Start measuring from zero when measuring length and ensure the scale is at zero before measuring the mass of an object.
• Ensure that your eyes are in line with your measurement when measuring the volume of a liquid or length.

Question 9

What causes the error of parallax?

Answer 9

The error of parallax is caused by the observer not being in direct line with the measurement being taken, The reading will be inaccurate.

Question 10

How do you avoid the zero error and the parallax error?

Answer 10

Zero error: start measuring at zero.

Parallax error: read the measurement at eye level.

Question 11

Define meniscus.

Answer 11

The meniscus is the curved surface showing the level of liquid.

Question 12

Fill in the missing answers:
A metre rule can be used to measure _____. The accuracy of a metre rule is _ __. This means that the metre rule can accurately measure ______ to the nearest ______. This will give _____ when one measures a ____ length, like the thickness of a ____.

Answer 12

A metre rule can be used to measure length. The accuracy of a metre rule is 1 mm. This means that the metre rule can accurately measure distance to the nearest millimetre. This will give problems when one measures a small length, like the thickness of a coin.

Question 13

What do you do when measuring the thickness, mass, or volume of a very small object?

Answer 13

To measure the thickness, mass, or volume of a very small object, measure a bigger number of objects and divide by that number.

Question 14

Why is it more accurate to measure the thickness of at least ten coins then calculate the average, than to measure the thickness of one coin?

Answer 14

The greater the number of coins used, the more accurate the value of the thickness of the coin.

Question 15

What do you do when measuring the mass of a liquid?

Answer 15

When finding the mass of a liquid, first measure the dry mass of the container, then the mass of the container and the liquid, then calculate the difference.

Question 16

Name the apparatus of the “to measure the mass of a liquid,” experiment.

Answer 16

• Triple beam balance or electronic scale.
• Measuring cylinder.
• Water.
• Calculator.

Question 17

Name the methodic steps to the “to measure the mass of a liquid,” experiment.

Answer 17

• Measure the mass of an empty measuring cylinder using a triple beam balance or electronic scale and record the measurement.
• Pour the liquid into the measuring cylinder and record the measurement.
• Minus the mass of the empty cylinder to the liquid-filled cylinder.

Question 18

What is volume?

Answer 18

Volume is the amount of space occupied by an object.

Question 19

What is the formula, unit, and symbol of the following derived units?

• Area.
• Volume.
• Density.
• Work.

Answer 19

Area

• length × width.
• square metre.
• m².

Volume

• length × width × height.
• cubic metre.
• m³.

Density

• mass/volume.
• gram per cubic centimetre.
• g/cm³.

Work

• force × distance.
• newton metre or joule.
• nm or J.

Question 20

What formula do you use to find the volume of a regular object?

Answer 20

Volume = length × width × height.

Question 21

What formula do you use to find the volume of water in a box?

Answer 21

Volume = length × width × depth.

Question 22

Name the apparatus for the volume of an irregular shape/object (stone) experiment.

Answer 22

• Thread.
• Measuring cylinder.
• Water.
• Calculator.
• Stone.
• Triple beam balance.

Question 23

Name the 4 methodic steps for the volume of an irregular shape/object (stone) experiment.

Answer 23

• Half fill a measuring cylinder with water and measure the volume using a triple beam balance.
• Tie a string around the stone and lower it.
• Allow the meniscus to settle and read the volume.
• Measure the displacement (Vstone = V2 - V1).

Question 24

Name the result for the volume of an irregular shape/object (stone) experiment.

Answer 24

• When the stone was lowered into the water, the water level rose.

Question 25

Why do we lower the stone with a string for the volume of an irregular shape/object (stone) experiment?

Answer 25

• The string prevents splashing.
• The cylinder breaking.
• It is easy to remove the stone.

Question 26

Fill in the missing spaces.
Different ______ have different _____ because the packing of their _____ is different. Objects with the same volumes may have different _____ because the particles may be more or less ____ ___. Generally, ____ have higher densities than _____ because their particles are ____ together and gases have the ____ density because their particles are spread out.

Answer 26

Different materials have different densities because the packing of their particles is different. Objects with the same volumes may have different masses because the particles may be more or less spread out. Generally, solids have higher densities than liquids because their particles are close together and gases have the least density because their particles are spread out.

Question 27

How is density defined?

Answer 27

Density is defined as mass per unit volume. It is a relationship between mass and volume.
Density = mass (g) / volume (cm³).

Question 28

Name the methodic steps to calculate the density of a regular solid (block of wood).

Answer 28

• First, measure the mass of the block.
• Measure the length, width, and height of the block using a ruler and record.
• Calculate the volume of the block (V = l × w × h).
• Calculate the density of the block (density = mass/volume (____g/cm³)

Question 29

Name the apparatus of finding the density of water experiment.

Answer 29

• Measuring cylinder.
• Water.
• Triple beam balance.

Question 30

Name the methodic steps of finding the density of water experiment.

Answer 30

• Measure the mass of an empty measuring cylinder.
• Add water to the measuring cylinder and measure the mass of the measuring cylinder + water.
• Read the volume of water in the measuring cylinder.

Question 31

Diagrams to study.

Answer 31

• Accuracy Diagram.
• Measure the volume of water in a box.
• Volume of an irregular shape.
• Area of a leaf.