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What is Buoyancy? not easy

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Presentation on theme: "What is Buoyancy? not easy"— Presentation transcript:

1 What is Buoyancy? not easy

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3 Boat challenge Cardboard ship Boats float

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5 The strength of the buoyant force on an object in water depends on the volume of the object that is underwater. As you keep pushing downward on the ball, the buoyant force gets stronger and stronger.

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7 Buoyancy

8 WATER PRESSURE ON BALL

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11 blue hole dive 4.3 min Tanya free dive CRAZY

12 Buoyant force of an object is equal to the weight of fluid displaced by the object
Increased pressure causes a decrease in volume of air

13 Buoyancy Buoyancy is a measure of the upward force a fluid exerts on an object that is submerged.

14 Three types of Buoyancy:
Positive = floating Neutral = Negative = sunk achieving nuetral bouyancy in pool Folding legs neutral

15 Spear fisherman walking on ocean floor
Deflating swim bladder PUFFER INFLATED saving puffer puffer caught in net Leave me alone

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18 VOLUME: Measure of the amount of space an object takes up
BASIC TERMS VOLUME: Measure of the amount of space an object takes up

19 MASS: measure of the amount of matter in an object

20 MATTER: anything that takes up space and has a mass, “the stuff objects are made of”

21 Volume and buoyancy The strength of the buoyant force on an object in water depends on the volume of the object that is underwater. As you keep pushing downward on the ball, the buoyant force gets stronger and stronger.

22 how boat floats how they float Bill Nye bouyancy
people vs boats not so bouyant bill nye top BOAT crashes photos boat crashes

23 Archimedes’ Principal
In the third century BC, a Greek mathematician named Archimedes realized that buoyant force is equal to the weight of fluid displaced by an object. HowStuffWorks Videos MythBusters Let's Talk Buoyancy.flv 3 min 1. Eureka! Episode 26 - Buoyancy.flv 5 min

24 “I FOUND IT” how he got idea

25 Archimedes Principle A body immersed in a fluid is buoyed up by a force equal to the weight of the fluid it displaces. 2016 launches FLIP How not to launch 25

26 Weight is a force, like any other pushing or pulling force, and is caused by Earth’s gravity. Weight is the downward force of gravity acting on mass. What is the rock’s weight? What is the rock’s mass?

27 boat design ping pong bouyancy ping pong part 2 ping pong part 3 ping pong part 4

28 Will it Float? What forces act on the object? Object 28

29 Will it Float? Weight = W B = Buoyancy Force 29

30 Will it Float? Weight = W B = 30

31 Will it Float? 31

32 Will it Float? Object Object Hovers 32

33 Will it Float? 33

34 Will it Float? Object Object Ascends 34

35 Will it Float? 35

36 Will it Float? Object Object Sinks 36

37 Sinking and floating Whether an object sinks or floats depends on how the buoyant force compares with the weight. 37

38 Cruise and storm Cruise hit waves Various rough seas and ocean liners oceanos people on cruise not so buoyant self righting boat sailboat overboard

39 Buoyancy The buoyant force works opposite the weight of an object. 39

40 Density and buoyancy If you know an object’s density you can quickly predict whether it will sink or float. Which ball will sink in water? Which ball will float in water? bowling ball 3min

41 Density and buoyancy When they are completely underwater, both balls have the same buoyant force because they displace the same volume of water. However, the steel ball has more weight since it has a higher density.

42 How Do Ships Float?

43 Ships Density of wood is about 0.5 to 0.8 g/cm3 so not surprising that wooden ships float. Density of iron 7.9 g/cm3. How is it that a battleship can float? 8-Jul-19 Physics 1 (Garcia) SJSU 43

44 How do boats/ships float?
Obviously the density of a metal boat or a is greater than the density of water, but they float because they contain a large amount of empty space. Because of their _______, they displace enough water to balance their own weight. shape

45 Boats and apparent density
Apparent density determines whether an object sinks or floats.

46 A solid block of steel sinks in water
A solid block of steel sinks in water. A steel ship with the same mass floats on the surface. ship design 46

47 Why did the Titanic Sink?
After it hit the iceberg, water began to fill the air filled compartments on the ship. The added weight of the water, combined with the weight of the ship became greater than the buoyant force supporting the ship. We all know what happened after that!

48 Iron Ships, Floating & Sinking
Iron ship floats since it is hollow inside. If water floods the inside then it sinks. 8-Jul-19 Physics 1 (Garcia) SJSU 48

49 Check Yourself Did the designers of this “water bridge” have to account for the weight of ships or just the water? 8-Jul-19 Physics 1 (Garcia) SJSU 49

50 Water Bridge in Germany

51 Six years to build it, 500 million euros later, and 918 meters long.....
This is a channel-bridge over the River Elbe and joins the former East and West Germany, as part of the unification project. It is located in the city of Magdeburg, near Berlin. The photo was taken on the day of inauguration. Did this bridge have to be designed to withstand the additional weight of ship and barge traffic, or just the weight of the water?

52 Answer: It only needs to be designed to withstand the weight of the water! 
Why?   A ship always displaces an amount of water that weighs the same as the ship, regardless of how heavily a ship may be loaded.

53 Will It Float? Ship Specifications: Weight = 300 million pounds
Dimensions = 100’ wide by 150’ tall by 800’ long Given Information: gW = 62.4 lbs/ft3

54 Assume Full Submersion:
FB = Vol x gW FB = (100’ x 150’ x 800’) x 62.4 lbs/ft FB = 748,800,000 lbs Weight of Boat = 300,000,000 lbs The Force of Buoyancy is greater than the Weight of the Boat meaning the Boat will float! How much of the boat will be submerged? Assume weight = Displaced Volume WB = FB 300,000,000 = (100’ x H’ x 800’) x 62.4 lbs/ft3 H = Submersion depth = 60.1 feet

55 Density and Ocean Currents
Did you know that there are underwater waterfalls in the ocean? While it may seem strange for water to fall through water, it really happens due to density differences in ocean water coming from different sources.

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57 1. Obtain one sheet of paper per group Put names on paper designate neatness hand writing as scribe.
2. Obtain ONE sheet of foil at a time 3. Obtain container of pennies (if you need more borrow) 4. Place paper towels under tub to catch water drips 5. Fill tub only half way

58 boyles law


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