Amman Baccalaureate School
IBMYP Science Department
Physics
Name: ________________________
Date: ________________
Grade 9
Section: ___________
Teacher’s Name: ______________
What are measurements?
Physics: is the science that deals with quantities
Have you ever wondered why a meter is a meter? Or what a cubit is? (A cubit was the length of
a man's arm from fingertips to elbow). Does this cause any problems if you tell someone how
large you want the door in a house measured in cubits? You are a tall man and you tell a short
man to build your doorway four cubits high.
Activity 1:
This question is to explore the standard system of units:
Use the information provided in the text and the video to answer the following answers:
Here's a quote from an article about ancient units
(https://www.britannica.com/science/cubit):
“Cubit, unit of linear measure used by many ancient and medieval peoples. It may have
originated in Egypt about 3000 BC; it thereafter became ubiquitous in the ancient world. The
cubit, generally taken as equal to 18 inches (457 mm), was based on the length of the arm
from the elbow to the tip of the middle finger and was considered the equivalent of 6 palms
or 2 spans. In some ancient cultures it was as long as 21 inches (531 mm)”.
Watch the following video: Youtube.com/watch?v=NValmBwli1Q
1) Outline what is meant by measurement.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2) Suggest some possible problems associated with the cubit unit. Is it standardized?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
3) Discuss with your group how you might overcome some of these problems.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Units in Science
Physical quantities: A physical quantity is anything that you can measure and consists of a
numerical magnitude and a unit. For example, length, temperature, distance and time are physical
quantities.
Physical quantities had many different types of units in the past. In the modern times, the units
have been standardized and are named the SI units, from the French “Le Systeme International
d’Unites” which means international system of units.
Physical quantities are classified into two types. There are fundamental and derived quantities.
Physical
Quantities
Fundamental
(basic)
Quantities
•
Derived
Quantities
Fundamental (Basic) Quantities: are those seven quantities that are considered to be so basic
that all other quantities need to be expressed in term of them.
Fundamental (Basic)
Quantities
SI Units
Name
Symbol
Length (L)
metre
m
Mass (M)
kilogram
kg
second
s
mole
mol
Temperature (T)
Kelvin
K
Current (I)
ampere
A
Luminous intensity
candela
cd
Time (t)
Amount of substance

Derived Quantities: are the quantities that can be derived from the fundamental quantities.
Derived units are products or quotients of the basic units.
Activity 2:
Find the derived unit for each of the below derived quantities.
Physics quantity
Equation
Area (A)
A = L2
Volume (V)
V = L3
Density (ρ)
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 = 𝑚𝑎𝑠𝑠/𝑣𝑜𝑙𝑢𝑚𝑒
𝜌 = 𝑀/𝑉
Velocity (v)
𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 = 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒/𝑡𝑖𝑚𝑒
𝑣 = 𝑠/𝑡
Acceleration (a)
𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 = 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦
/𝑡𝑖𝑚𝑒
𝑎 = 𝛥𝑣/𝑡
Force (F)
𝐹𝑜𝑟𝑐𝑒 = 𝑚𝑎𝑠𝑠 × 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛
𝐹 = 𝑀 × 𝑎
Derived SI Units