Unit notes and practice questions
Everything here is for unit 2 of the Grade 9 Physics textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.
The cards filed under this chapter on the Grade 9 Physics page. Open one at a time.
| Prefix | Symbol | Factor |
|---|---|---|
| tera | T | |
| giga | G | |
| mega | M | |
| kilo | k | |
| centi | c | |
| milli | m | |
| micro | ||
| nano | n | |
| pico | p |
When you use it
Use when converting very large or very small measurements into standard powers of 10.
Watch out
Micro uses the Greek letter for , while milli uses m for . Do not confuse the symbols.
Drafted from Grade 9 Physics, pages 12-35, then checked twice before it went up
When you use it
Use to classify physical quantities based on whether direction is required along with magnitude.
Watch out
Distance and speed are scalars, but displacement and velocity are vectors. Mass is a scalar, whereas force is a vector.
Drafted from Grade 9 Physics, pages 12-35, then checked twice before it went up
| Physical quantity | Symbol | SI Unit | Unit Symbol |
|---|---|---|---|
| Length | meter | m | |
| Mass | kilogram | kg | |
| Time | second | s | |
| Temperature | kelvin | K | |
| Current | ampere | A | |
| Amount of substance | mole | mol | |
| Luminous intensity | candela | cd |
When you use it
Use this reference to identify the seven base physical quantities and their standard SI units.
Watch out
Speed, force, and density are derived quantities. Only these seven cannot be defined in terms of other quantities.
Drafted from Grade 9 Physics, pages 12-35, then checked twice before it went up
When you use it
Use when identifying valid mathematical operations on interval and ratio measurement scales.
Watch out
Celsius and Fahrenheit are interval scales without a true zero, so values cannot be multiplied or divided. Only the Kelvin scale is a ratio scale with an absolute zero.
Drafted from Grade 9 Physics, pages 12-35, then checked twice before it went up
10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.
Question 1
Which type of measurement scale has equal intervals and a true zero point, allowing addition, subtraction, multiplication, and division?
Answer: D Ratio scale
Why
A ratio scale has equal intervals and a true zero point. This allows all four basic arithmetic operations: addition, subtraction, multiplication, and division.
Question 2
Which of the following is one of the seven fundamental (basic) physical quantities in physics?
Answer: A Mass
Why
Mass is one of the seven fundamental quantities. Speed, density, and force are derived quantities because they are calculated from basic quantities.
Question 3
Which of the following is classified as a vector quantity?
Answer: C Acceleration
Why
A vector quantity has both magnitude and direction. Acceleration has both magnitude and direction, while distance, time, and mass have only magnitude (scalars).
Question 4
Which rule must students always follow in a physics laboratory?
Answer: C Always wear lab safety goggles
Why
According to laboratory safety rules, you should always wear lab safety goggles, never work alone, and never taste chemicals.
Question 5
How many significant figures are in the number 2000.0?
Answer: C 5
Why
Zeroes at the end of the decimal part are counted as significant figures. Therefore, 2000.0 has 5 significant figures.
Question 6
Which unit prefix represents a multiplier of 10-6 (0.000001)?
Answer: B micro
Why
The prefix micro (µ) corresponds to the factor 10-6. Milli is 10-3, nano is 10-9, and pico is 10-12.
Question 7
The standard SI unit of time, the second (s), is defined by which of the following?
Answer: B 9 192 631 770 periods of vibration of radiation from the cesium-133 atom
Why
The second (s) is defined as 9 192 631 770 times the period of vibration of radiation from the cesium-133 atom.
Question 8
A student in Hawassa spent 3 hours + 10 minutes + 120 seconds doing homework. How many minutes is this total time?
Answer: B 192 min
Why
Convert each part into minutes: 3 hours = 3 × 60 = 180 min; 120 seconds = 120 / 60 = 2 min. Total = 180 + 10 + 2 = 192 minutes.
Question 9
A trader in Addis Ababa measures three separate sacks of teff. The masses are 2 tonnes, 100 kg, and 1 kg. What is the total mass in kilograms?
Answer: C 2101 kg
Why
Since 1 tonne = 1000 kg, 2 tonnes = 2000 kg. Adding the masses: 2000 kg + 100 kg + 1 kg = 2101 kg.
Question 10
Which derived physical quantity has the SI base unit combination of kg / (m · s2)?
Answer: B Pressure
Why
Pressure is defined as Force / Area. Its SI unit is the pascal (Pa), which is equal to kg / (m · s2).
The app holds 12 questions on this unit, marked as you go. These are the first 10.
Unit 2 runs from page 12 to page 35 of the Ministry of Education edition.
Ministry of Education edition, English, 179 pages
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