The document discusses the tools and units used to measure weight and mass, highlighting that weight is measured in newtons using a spring scale, while mass is measured in grams using a balance scale. It explains that weight varies with gravity, while mass remains constant regardless of gravitational changes. The document provides procedures for measuring both weight and mass effectively.

1. MEASURING WEIGHT
AND MASS
Moira Whitehouse PhD

2. MEASURING WEIGHT
TO MEASURE MOST ANYTHING ONE
NEEDS SOME TOOL WITH WHICH TO
MEASURE AND A STANDARD UNIT
OF MEASUREMENT.

3. •THE TOOL WE USE TO MEASURE
WEIGHT IS A SPRING SCALE.
•THE STANDARD UNIT
OF MEASUREMENT
USED IN SCIENCE IS
THE NEWTON.

4. •BEFORE SERIOUS TALK ABOUT THE
SPRING SCALE, LET’S REVIEW THIS
IDEA CALLED WEIGHT.
•YOU SHOULD REMEMBER THAT
THE WEIGHT OF AN OBJECT IS A
MEASURE OF HOW HARD GRAVITY
IS PULLING ON THE OBJECT.
•THE HARDER GRAVITY PULLS ON
SOMETHING, THE MORE IT WEIGHS.

5. •WHEN WE PICK UP ANYTHING WE
ARE WORKING AGAINST GRAVITY.
•IF WE FOUND OURSELVES ON THE
MOON WHERE THE GRAVITY WAS
LESS, WE WOULD SUDDENDLY SEEM
TO BE A LOT STONGER.

6. •KNOWING THAT WEIGHT DEPENDS
ON GRAVITY WE CAN SEE THAT ANY
TOOL TO MEASURE WEIGHT MUST
SOMEHOW ACCOUNT FOR EARTH’S
GRAVITY.
•THE SPRING SCALE DOES
THAT BY HAVING A SPRING
THAT IS ADJUSTED TO BE
JUST AS STRONG AS THE
PULL OF EARTH’S GRAVITY.

7. •THE PROCEDURE
TO
MEASUREWEIGHT
IS TO SUSPEND
THE OBJECT FROM
A SPRING SCALE
AND READ THE
WEIGHT IN
NEWTONS (n)
FROM THE SCALE

8. WE NEEDED TWO THINGS TO
MEASURE WEIGHT, ONE WAS A
TOOL AND THE OTHER WAS:
TO MEASURE MOST ANYTHING ONE
NEEDS SOME TOOL WITH WHICH TO
MEASURE AND A STANDARD UNIT
OF MEASUREMENT.
•THE UNITS USED TO MEASURE
WEIGHT IN THE METRIC SYSTEM
ARE NEWTONS (n).

9. •SO WHAT IS THIS UNIT OF
MEASUREMENT THAT IS NAMED FOR
THE GREAT SCIENTIST ISAAC NEWTON?
•LIKE OTHER UNITS IN THE METRIC
SYSTEM, THE NEWTON IS DERIVED
FROM THE METER AND BY USING THE
MASS OF WATER, THE EARTH’S MOST
COMMON COMPOUND.
(ONE 10 MILLIONTH OF THE DISTANCE
FROM THE NORTH POLE TO THE
EQUATOR)

10. THIS MUCH
WATER
1 GRAM 100 GRAMS
X 100
EQUALS
= AND = ONE
NEWTON
IN EARTH’S GRAVITY

11. •WITH THAT BIT OF INFORMATION
ABOUT THE SPRING SCALE AND THE
NEWTON, LET’S GET SOME
PRACTICE READING A SPRING
SCALE.
•THE RED SCALE IS USED TO
MEASURE LIGHTER OBJECTS AND
HEAVIER OBJECTS CAN BE WEIGHED
WITH THE BLUE SCALE.

16. •REMEMBER, IT IS IN EARTH’S
GRAVITY THAT ONE NEWTON IS
EQUAL TO ABOUT 100 GRAMS.
•SO, IF THE VALUE OF GRAVITY
CHANGED, SAY ON ANOTHER
PLANET, THE VALUE OF THE
NEWTON WOULD ALSO CHANGE.
•THAT OFTEN MAKES THE CONCEPT
OF WEIGHT UNSATISFACTORY FOR
SCIENTIFIC WORK.

17. •FOR THEIR WORK, SCIENTISTS
NEED INFORMATION ABOUT STUFF
THAT DOES NOT CHANGE AS
GRAVITY CHANGES.
•AND THEY FOUND IT IN THE
CONCEPT CALLED.... MASS.

18. MEASURING MASS
• AGAIN, TO MEASURE MOST
ANYTHING ONE NEEDS SOME TOOL
WITH WHICH TO MEASURE AND A
STANDARD UNIT OF MEASUREMENT.

19. •THE TOOL WE USE TO MEASURE
MASS IS A BALANCE SCALE.
•THE STANDARD UNIT OF
MEASUREMENT USED IN SCIENCE IS
THE GRAM.

20. •BEFORE GOING INTO THE NITY
GRITTY OF MEASURING MASS, WE
NEED AN UNDERSTANDING OF JUST
WHAT MASS IS.
•MASS IS THE AMOUNT OF
MATTER IN AN OBJECT.

21. •MASS IS DIFFERENT THAN EITHER
SIZE OR VOLUME.
•THE OBJECT ON THE LEFT, ALTHOUGH
MUCH BIGGER, HAS JUST THE SAME
MASS AS THE TWO SMALL ROCKS ON
THE RIGHT.

22. •MASS IS MORE USEFUL TO SCIENTISTS
THAN WEIGHT BECAUSE AN OBJECT’S
MASS REMAINS CONSTANT REGARDLESS
OF THE AMOUNT OF GRAVITY.
•THE REASON THAT THE MASS OF
OBJECTS ON A BALANCE SCALE IS NOT
AFFECTED BY CHANGES IN GRAVITY IS
THAT THE SAME GRAVITY IS PULLING
ON BOTH SIDES OF THE BALANCE.

23. •IF EACH TRAY HAS THE SAME
AMOUNT OF MATTER...REGARDLESS
OF SHAPE OR VOLUME.
GRAVITY PULLS EQUALLY ON EACH
OF THEM AND THE TRAYS STAY
BALANCED.

24. •BUT IF ONE OBJECT HAS MORE MASS
THAN THE OTHER:
YOU KNOW WHAT’S GOING TO HAPPEN.

25. •SURE, THE MORE MASSIVE OBJECT,
BEING PULLED HARDER BY GRAVITY,
WILL GO DOWN AND THE LESS
MASSIVE OBJECT WILL GO UP.

26. •IF WE BALANCE AND UNKNOWN
OBJECT IN THE RED TRAY WITH
KNOWN MASSES IN THE YELLOW TRAY
WE WILL LEARN THE MASS OF THE
OBJECT IN THE RED TRAY.

27. •BUT WHERE DO WE FIND THESE
“KNOWN” MASSES?
WE USE PIECES OF BRASS MARKED
WITH THEIR MASS AS STANDARD
UNITS OF MASS.

28. •LIKE THESE:

29. •WE HAVE THE TOOL (A BALANCE
SCALE) AND THE STANDARD UNIT (THE
GRAM), THE ONLY OTHER THING WE
NEED TO FIND THE MASS OF AN
OBJECT IS A PROCEDURE.
•THE PROCEDURES IN THE FOLLOWING
SLIDES ARE BASIC, BUT THEY WORK.

30. 1. PLACE THE OBJECT IN ONE TRAY.

31. 2. PLACE THE LARGEST MASS IN THE
OTHER TRAY.

32. •THE 500g MASS IS THE GREATER
THAN THE MASS OF THE PUMPKIN, SO
REMOVE IT AND PLACE THE SECOND
LARGEST PIECE OF STANDARD MASS.

33. 3. PLACE THE SECOND LARGEST MASS
IN THE OTHER TRAY.

34. •THE 200g MASS IS ALSO GREATER
THAN THE MASS OF THE PUMPKIN, SO
REMOVE IT AND PLACE THE THIRD
LARGEST PIECE OF THE STANDARD
MASS ON THE TRAY.

35. 3. PLACE THE THIRD LARGEST MASS IN
THE OTHER TRAY.

36. •AH, THE 100g MASS IS LESS THAN THE
MASS OF THE PUMPKIN, SO LEAVE IT
AND ADD THE NEXT LARGEST PIECE OF
STANDARD MASS ON THE TRAY.

37. OK, THE 100g AND 50g MASSES ARE
EQUAL TO THE MASS OF THE
PUMPKIN.

38. •IT MAY TAKE A FEW MORE STEPS TO
EXACTLY BALANCE THE MASS OF YOUR
OBJECT.
•KEEP USING THE SAME PROCEDURE:
ADD THE NEXT LARGEST UNIT AND IF
THAT IS TOO MUCH, REMOVE IT AND
SELECT THE NEXT LARGER UNIT.

39. •WHEN THE OBJECT AND THE MASS
UNITS ARE BALANCED, LINE UP THE
MASS UNITS FROM THE LARGEST TO
THE SMALLEST.
•TOTAL THE VALUES OF THE THE MASS
UNITS AND BINGO, YOU KNOW THE
MASS OF THE OBJECT.

40. •THERE ARESOME BALANCE SCALES
WITH SLIDERS THAT CAN BE USED TO
MOVE GRADUATED AMOUNTS OF
MASS TO BALANCE THE OBJECT.
•THESE ALLOW THE MASS OF THE
OBJECT TO BE READ DIRECTLY FROM
THE SLIDERS.

41. •MORE ADVANCED BUT EVEN MORE
DISTANT FROM “BALANCING” MASSES,
IS THE TRIPLE BEAM BALANCE.

42. •YOU READ THIS SCALE BY NOTING
WHERE THE SLIDER POINTERS ARE
AND TOTALING THOSE NUMBERS.
RIGHT, 161 GRAMS

43. THERE YOU HAVE IT:
MEASURING WEIGHT
AND MASS

44. •STUDY •YOU CAN
SCIENCE AND LEAP HIGH
WHEN YOU AND WEIGH
GROW UP YOU LESS, BUT
MAY GET A DON’T
CHANCE TO FORGET, YOUR
GO THE MASS WILL
MOON STILL BE THE
WHERE: SAME.