A presentation on recently changed nature's constant to redefine SI units which created new standards for reading units.

1. THE KG IS DEAD
Is the kilogram really a kilogram?
SUBMITTED BY –
Ajaypal Singh
Siddhrajsinh Parmar
SUBMITTED TO –
Department of Mechanical Engineering

2. INTERNATIONAL
BUREAU OF
WEIGHTS AND
MEASURES
16 Nov 2018
60 Nation Representatives
Met in Versailles, France
Vote to change the definition of a ‘KILOGRAM’

3. System
International
Units
• Kilogram - mass
• Candela – luminous intensity
• Kelvin - temperature
• Second - time
• Mole - substance
• Meter - length
• Ampere - current
After this, all SI units will be based on fundamental
constants of nature and not physical artifacts.

4. METRIC SYSTEM
GRAVE: Latin ‘gravitas’, means ‘weight’
o Basic unit of mass
o Grave = 1000 × gramme
o Grave = kilogram
In 1799, the kg definition was refined to be the
mass of a liter of water at 4°C (where water is
most densest).
A pure platinum cylinder was created to have the
same mass as the water definition called to be
“KILOGRAM OF THE ARCHIVES”.

5. INTERNATIONAL
PROTOTYPE KILOGRAM
o It was the definition of kilogram.
o Its French name is “Le Grand K” or “Big K”.
o Only SI unit defined by a physical object.
In 1889, the kilogram was upgraded to a
(identical) platinum-iridium alloy cylinder.

6. IPKs DISTRIBUTION
It sits under 3 bell jars, next to 6 sister
kilograms, in a climate controlled vent in
IBWM, Paris
40 identical replicas were also made with
slight recorded variations, these were sent to
countries around the world to serve as their
national standard.
In 1948 and 1990, the kilograms were reunited
for weigh-in, their masses had diverged up to
50 μg over time, same as six sister cylinders
stored with it.

7. 1 KG Silicon Sphere – 28 atoms
(1 isotope of silicon)
o Investment : 1 million Euro
o Reason for sphere : its diameter can define
its overall dimension
o Measurement : Laser ray
o Volume =
𝜋 ⅆ3
6
o 1 kilogram = mass of 2.15 × 1025
silicon – 28 atoms
WORLD’S
ROUNDEST
OBJECT

8. SOLUTION
FIX THE PLANCK’S CONSTANT TO A DEFINITE VALUE
We know, 𝑬 = 𝒉𝒇
Energy of photon = Planck’s constant X Frequency of Photon
We also know, 𝑬 = 𝒎𝒄 𝟐
Therefore, 𝑬 = 𝒉𝒇 = 𝒎𝒄 𝟐
[Planck’s constant is involved in mass]
𝒎 =
𝒉𝒇
𝒄 𝟐
Problem: Planck’s constant is uncertain
• If the value of Planck’s constant is fixed, then

9. SCIENTIFIC EFFORTS
Scientists around the world have used multiple different techniques and
equipment to measure Planck’s constant as accurately as possible.
One of the major methods, use of a watt balance or
“Kibble Balance”, where weight of a kg is balanced with the
force from an electromagnet.

10. WATT BALANCE GRAPH

11. NEW CONSTANTS
THE 7 UNITS OF METRIC SYSTEM AND THEIR
FUNDAMENTAL CONSTANTS
METER
Length: Distance travelled by light in vacuum
in 1/299, 792, 458 seconds
SECOND
Time: Exactly 9, 192, 631, 770 cycles of
radiation of an atom of caesium-133
KILOGRAM
Mass: new Planck’s Constant 6.62607015 ×
𝟏𝟎−𝟑𝟒
Js
MOLE
Amount of substance: new Avagadro’s
constant 6.02214076 × 1023
molⅇ−1
KELVIN
Temperature: new Boltzmann constant
1.380649 × 10−23
J/K
AMPERE
Current: equal to the flow of 1.602176634 ×
10−19
electrons
CANDELA
Luminous Intensity: light source with
monochromatic radiation of frequency 540 ×
1012 Hz and radiant intensity of 1/683 watt per
steradian

12. DAILY LIFE
IMPACT
WILL THESE NEW DEFINITIONS CHANGE ANYTHING?
For most people, NO!
But for Scientists, YES!
KG, temperature, current, etc. are still going to work
the same.
The point of this definition change is not to shake
things up, but to keep things consistent & reliable
forever with precise measurements.

13. THANK YOU!

14. THANK YOU!