PS- 1.3

1. PS- 1.3 Scientific Measurements

2. Bad Joke….. • Why did the bottle insist on being at the front of the shelf?

3. Because it was a liter, not a follower!

4. Why was a system needed? • Long ago, parts of the human body were often used as units of measure. • Egyptian “cubit” was the length from your elbow to the tip of your middle finger.

5. The length of the kings foot or the distance from the tip of his nose to his fingertips were common units of measurement.

6. See any obvious problems with this line of thought? • Different from country to country • Existing measurements would change each time a new king was crowned • Different from body part to body part

7. The metric system was created with the purpose of establishing a universal system of measurement that could easily be used by people all over the world regardless of their country of origin.

8. Metric System Facts • Developed by the French in late 1700s and was officially adopted in 1790. • Named “Le Systeme International d’Unites”; Abbreviated SI • Was initially forced on all countries. • The option for people to use the metric system or not in the US became legal in 1866.

9. Metric System Facts Cont’d: • USA opted out of using the system. • USA is the only technologically advanced country NOT using the Metric System as it’s main system of measurement; Still using the English System which is a combo • Especially important to scientists

10. Metric System Facts Cont’d: • Decimal based system ~ What the heck does that mean? • It’s based on powers of 10, so it is very simple to use

11. The Metric units most often used by average people are…. • Meter: measures length • Second: measures time • Gram: measures mass • Liter: measures volume • Degree Celsius: measures temperature YOU WILL SEE THIS AGAIN!!

12. Regardless of the unit, the entire metric system uses the same prefixes.

13. Most common prefixes • Kilo – 1000 Deci – 1/10 or 0.1 • Hecto – 100 Centi – 1/100 or 0.01 • Deka – 10 Milli – 1/1000 0r 0.001 • Meter/gram/liter – 1 “King Henry’s Daughter Usually Drinks Chocolate Milk”

14. Length • Length is the distance between 2 points • The SI base unit for length is the meter

15. Length • We use rulers or meter sticks to find the length of objects.

16. Mass • Mass is the amount of matter that makes up an object. • The SI unit for mass is the gram. • The mass of an object will not change unless we add or subtract matter from it.

17. Mass • A golf ball and a ping pong ball are the same size, but the golf ball has a lot more matter in it. Which has more mass? ~the golf ball has more mass

18. Mass • A paper clip has a mass of about one gram • Remember: the mass of an object will not change unless we add or subtract matter from it.

19. Measuring Mass • We will use a triple beam balance scale to measure mass. • Gravity pulls equally on both sides of a balance scale, so you will get the same mass no matter what planet you are on.

20. Weight • Weight is a measure of the force of gravity on an object. • The SI unit for weight is the Newton (N). • The English unit for weight is the pound

22. Gravity • Gravity is the force of attraction between any two objects with mass. • Gravity depends on 2 things: Distance and Mass

23. Gravity • More distance = less gravity= less weight • Less distance = more gravity = more weight • More mass = more gravity = more weight • Less mass = less gravity = less weight

24. Weight vs Mass

25. ** Notice that Jill’s mass never changes**Jill is a 30 kg little girl no matter where she goes or what planet she is on.

27. Volume • Volume is the amount of space contained in an object. • We can find the volume of box shapes with this formula V = L x W x H

28. Volume Cont’d… • In the case of box shapes, the units would be cubic centimeters (cm³). • So, a box that is 2cm x 3cm x 5cm would have a volume of…… 30 cm³

29. Base Units • The base unit for volume is the Liter. • We measure volume with a graduated cylinder.

30. Graduated Cylinders • Liquids form curved, upper surfaces when poured into graduated cylinders (sticks to the sides) • To correctly read the volume, read the bottom of the curve called the meniscus

31. Liquid Volume • When the metric system was created, they decided that 1 cm³ of water would equal 1 milliliter of water. • That 1ml of water would have a mass of one gram. • 1cm³ water = 1ml water = 1 gram of water

32. Water Displacement • You can use water displacement to find the volume of objects that are not box shaped.

33. Water Displacement • We can put water in a graduated cylinder. If a rock causes the level to rise from 7 ml to 9 ml, the rock must have a volume of 2ml.

34. Water Mass and Volume • Remember: 1 cm³ = 1 ml = 1 g • What would be the mass of 50 ml of water? 50 grams • How many milliliters would you have if you were given 23 cm³ of water? 23 ml

35. Density • Density is the amount of matter (mass) compared to the amount of space (volume) an object occupies. • We will measure mass in grams and volume in ml or cm³

36. Density Formula • Density is mass divided by volume Density = mass / volume • Remember: all fractions are division problems

37. Density Triangle • Cover the property you are trying to find, and do what is left. • To find density, cover the word density. • You have mass over volume left. So divide mass by volume to find density

38. Density Triangle • To find mass, you cover the word mass and do what is left. • You have density x volume left

39. Density Triangle • To find volume, cover volume. • You have mass over density left, so you divide mass by density to find volume

40. Water and Density • Since 1 gram of water has a volume of 1 ml, then the density of water will always be 1 g/ml. • Ex: A kg of water will have a volume of 1000 ml, so it’s density will be 1 g/ml. 1000g/1000ml = 1 g/ml

41. Floating vs Sinking

42. Floating vs Sinking • Remember: density of water is 1 g/ml • Less dense materials will float on top of more dense materials.

43. Floating and Sinking • Objects with a density of less than 1 g/ml will float on top of water. • Objects with a density greater than 1 g/ml will sink in water.

44. Neutral Buoyancy • Objects with a density = to the density of water will float in mid water, at whatever level you place the object • Fish and submarines control their depth by changing their density

45. Titanic sails the ocean blue

46. Titanic makes it’s maiden voyage. • What is the density of this enormous, steel hulled ship, dull of machinery, coal, people and all sorts of heavy things? ~It’s floating, so we know that it’s density has to be less than 1 g/ml. • How can that be? ~It is a hollow vessel that is full of air.

47. Wreck of the Titanic • The denser the ship became, the lower it settled into the water. • What is the density of the ship resting on the ocean floor? ~must be over 1 g/ml to have gone below the surface

48. Review • How much does the prefix Hecto- represent? ~ 100 • What is the SI unit for measuring length? ~ meter • What 2 things does the force of gravity depend on? ~ mass and distance

49. Review • What are the 2 units that volume can be measured in? ~ cm³ for box shapes ~ml for liquids • What is the density of water? ~ 1 g/ml

50. Dimensional Analysis is a way to convert measurements between different units to help compare them.