1. ICEBERGS FLOAT !
WHY ?
John Parkinson

2. What forces are acting on the iceberg?mg U
John Parkinson
What can you say about mg and U?

3. Why ?? IT DOES ON MERCURY! DOES WOOD FLOAT? DOES IRON FLOAT?
Density Order:
solid > liquid >>> gases
USUALLY ! !
John Parkinson

4. BOTH BOXES CONTAIN BALLS OF THE SAME MASS
BOX A
BOX B
BOTH BOXES CONTAIN BALLS OF THE SAME MASS
ONE BOX SINKS WHEN IT IS PLACED IN WATER - WHICH?
BOX B SINKS BECAUSE THE BALLS ARE MORE D Y PACKED
DENSELY
kg m-3
UNITS ??
John Parkinson

5. M
V 
John Parkinson

6. one atmosphere pressure
Is a liquid denser than a solid?
ICE IS SOLID WATER, so why does it float on water?
temperature / 0C
density / kg m-3
1000
Why does ice form on the top of a pond and not on the bottom during cold weather ?
Water density at
one atmosphere pressure
ice
water
992
WATER IS MOST DENSE AT 40 C
John Parkinson

7. POND IN WINTER I bet its cold up there! Air at below zero Ice at 00C
Water at 10C
Water at 20C
Water at 30C
Water at 40C
John Parkinson

8. ARRANGEMENT OF MOLECULES IN WATER
ICE [SOLID WATER]
LIQUID WATER
STEAM
John Parkinson

9. Hence a floating body must displace its own weight of fluid”
Archimedes’ Principle
“A body immersed in a fluid experience an upward buoyant force [an upthrust] equal to the weight of the fluid it displaces”
EUREKA ! U
Hence a floating body must displace its own weight of fluid” mg
John Parkinson

10. The QM2 has a displacement of 150 000 tonnes
John Parkinson

11. UNITS
How many square centimetres in 1 square metre?
100 cm
1 m
1 m2 =
100 cm
1 m
1 m2
100 cm x 100 cm
= cm2
Likewise 1 m2 = ? mm2
John Parkinson

12. It is easier to work in metres from the start
1 m3 = 100 cm x 100 cm x 100 cm 1m
1 m3 = cm3 1m 1m
A cuboid has dimensions of 40 cm x 50 cm x 80 cm. What is its volume in cubic metres?
It is easier to work in metres from the start
0.40 x 0.50 x = 0.16 m3
John Parkinson

13. DEPLETED URANIUM
Depleted Uranium (DU) is what is left from natural uranium when most of the radioactive isotopes U234 and U235 have been removed. Depleted Uranium is forty percent less radioactive than the natural "background" uranium that is prevalent in the earth's air, water and soil. Depleted Uranium is hard and dense; it is almost twice as dense as lead.
What is DU used for?
Due to it density, [19050 kg/m3 ] depleted uranium is used in aprons to protect patients in hospitals and dentists' offices from excessive x-rays, and as ballast in 747 planes and in the keels of large sailboats.
Again, because of its strength and density, depleted uranium is sometimes used in defensive plating on armored vehicles and other platforms to deflect ammunition rounds that might otherwise kill or wound personnel inside the vehicle. It has been a component in munitions [ shell tips ] used against hostile tanks and other armored vehicles.
John Parkinson

14. What is the density of a black hole?
General Relativity suggests that, as an object collapses to form a black hole, it will eventually reach a point of infinite density. This really means that the theory of relativity breaks down at this point. We do not know what happens at the centre of a black hole. We need a theory of quantum gravity to predict this.
John Parkinson