Future Fleet Science Topics: Buoyancy, Density and Volume

1. Future Fleet Science Topics: Buoyancy, Density and Volume

2. Future Fleet

3. SESSION ONE

4. History of Failed Ships

5. Student Responses History of Failed Ships • What is the economic cost of a failed ship design?

6. Student Responses History of Failed Ships • What is the human cost of a failed ship design?

7. Student Responses History of Failed Ships • How can the tragic losses in the article be prevented?

8. Student Responses History of Failed Ships • Is it possible to know how much a ship will cost before you build it?

9. Student Responses History of Failed Ships • Can an unsinkable ship be designed?

10. Student Responses History of Failed Ships • Is it possible for a tragedy at sea to happen today, even with current technology?

11. Lets Explore

12. Exploration Teams • Assigning the teams • Roles • Task manager • Activity recorder • Life Line • Evaluator

13. Task manager • Keep group members focused

14. Activity recorder • Records what the group does and what questions the members have

15. Life Line • Can leave the group to seek help

16. Evaluator • Judge the effectiveness of the group • Report back only to the group

17. The Stations • How Metal "Boats" Float (5 min) • Liquid Density and Lava Lamp (5 min) • Soda Can Pirouette (5 min) Students should move to their teams now and begin the exploration

18. TIME IS UP Please return to your seats

19. Student Responses REPORT • Each group should now report on the following: • Name one thing you learned that has not been mentioned yet

20. Definitions and Calculations • Density • Displacement Mass • Buoyancy • Center of Gravity • Center of Buoyancy • Metacenter

21. Density • The degree of compactness of a substance • Mass per unit of Volume D = M / V Solve the equation for mass M = D x V Mass can now be calculated

22. The Density of Water Density is influenced by depth, temperature, and salinity. Look at the Salinity Map Look at the Temperature Map Salinity Map Temperature Map

23. Displacement Mass The mass of a fluid (as water) displaced by a floating body (as a ship) of equal mass To stay afloat A 460 mega kilogram ship Needs to Displace 460 mega kilograms of water

24. The Calculation of Displacement Mass 1) Find the density of water of operational area Density is influenced by depth, temperature, and salinity We will use about 30 degrees Celsius as an operational area We will use about 34 PSU* Salinity as an operational area Temperature Map Salinity Map At 20m depth the density will be 1.021 g/cm3 *PSU * Salinity is measured by conductivity (how easily electricity flows through a seawater sample).

25. The Calculation of Displacement Mass 2) Find the volume of water being displaced Take the cross sectional area height x width 30 m x 5m x 3m and multiply by the 3rd dimension to find volume 30m 5 m 3 m This gives us a Volume of 450 m3

26. The Calculation of Displacement Mass 3) Find the displacement mass M = V x D Volume of Water (cm3) x Density (g / cm3) (450 m3 x 1,000,000 cm3 / m3 ) x 1.021 g/cm3 459450000 g

27. Weight vs. Mass - Weight is a force - Force in general is mass times acceleration So the volume can displace a mass of 459450000 grams or a weight of 459450000 g x (1kg/1000 g) * 9.8 m/s2 = 4,502,610 N or 459450000 g x (1kg/1000 g) * 2.2lbs/kg= 1,010,790 lbs or 505.4 Tons

28. Buoyancy What is Buoyancy? Buoyancy is the upward force that a fluid exerts on an object less dense then itself. As mass is added, the boat displaces more water until the weight of the displaced water equals the weight of the boat; then the boat sinks.

29. Archimedes's principle. An object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object. Put picture of floating boy here

30. Summary of Buoyancy and Displacement 30m 5 m 3 m A 500 Ton ship needs to displace a volume of 450m3 to avoid sinking

31. Displacement of irregular shapes Use graph paper to approximate the cross sectional area Then find the displacement mass

32. Center of Gravity What is the Center of Gravity? The center of gravity is the geometric property that represents the average location of the weight of an object. We can balance the scale by moving the fulcrum to the center of gravity.

33. How do we find the Center of Gravity? • Hang the object from a point • Hang a weighted string from the point and when it comes to a rest draw a line • Repeat with another point on the shape

34. Center of Buoyancy • Is the center of gravity of the displaced water • The center of buoyancy changes as the ship rolls and pitches • The balance between center of buoyancy and center of gravity affects stability of the ship

35. Metacenter Ship Water

36. Center of Gravity Center of Buoyancy

37. Ship rolled at a small angle

38. Line of force for new center of buoyancy perpendicular to water line New center of buoyancy

39. The intersection of the two lines of force form the metacenter

40. The distance from the metacenter (M) to the center of gravity (G) is called the metacentric height (GM). M G

41. Metacenter • A positive GM is needed to make a stable ship • The higher the GM the more stable the ship • The higher the GM the faster the ship will right itself. If this number becomes too high the ride will become rough.

42. Elaborate • Work in your teams to come up with general guidelines for ship design.

43. Student Responses Exit Ticket • Find the displacement of mass of a ship segment with cross sectional dimensions of 30m by 8 m and a length of 10m.

44. SESSION TWO Build a Prototype

45. The Littoral Class • Future Ships of the Navy

46. Student Responses The Littoral Class • Why did the Navy use two different designs?

47. Student Responses The Littoral Class • What need is the Navy trying to address?

48. Student Responses The Littoral Class • What aspects of the design of the ships address the needs of the Navy?

49. Student Responses The Littoral Class • Why do you think using all new 21st century technology was important to these features?

50. LCS and Pirates Click me to see Somalia Click me To see video