1. PRESSURE in WATER F = force exerted by water against submersed body F = force exerted by water against submersed body  A = area of that body over which F is applied  water pressure = mass of water above body  pressure  with depth [ weight of the water  ]  FIG D.6 on page 99

2. WD: Weight Density of Water Wt. Density (WD) = weight per unit volume Wt. Density (WD) = weight per unit volume Salt Water has more wt. density than fresh water due to salt giving more mass to the water Salt Water has more wt. density than fresh water due to salt giving more mass to the water Water is NOT compressible / Air IS compressible Water is NOT compressible / Air IS compressible density of water does not change with depth density of water does not change with depth air density does change as follows:  altitude,  temperature =  density of air air density does change as follows:  altitude,  temperature =  density of air

3. DENSITY Lower than Water Higher than Water Air Air Fat Fat Bone 50% more dense Muscle slightly more dense

4. ARCHIMEDES Principle  Upward buoyant F = to volume of displaced water  Floating - body Wt. Density = to OR < than water WD  Sinking - body Wt. Density > than water WD

5. FIG 14.2b Positive Buoyancy FIG 14.2c Negative Buoyancy

6. Positive Buoyancy Negative Buoyancy Figure 14.2b Figure 14.2c Net Forces  0 Net Forces  0 water WD  than body water WD  than body body WD  than water body WD  than water body WD  due to more fat tissue body WD  due to more fat tissue Net Forces  0 water WD  body WD  body WD  due to less fat, more muscle

7. CB: Center of Buoyancy  center of the volume of displaced water  Force of buoyancy acts at CB  CG and CB co-linear = Float  CG and CB out of line rotation occurs due to F gravity pushes  while F buoyancy pushes   pitching effect results with rotation @ CB

8. Conditional Floater True Floater lungs inflated = Floats lungs inflated = Floats lungs deflated= Sinks lungs deflated= Sinks when “drown-proofing” when “drown-proofing” 1. Exhale then Inhale 2. Long hold of air 3. CG close to CB Floats with or without inflated lungs fat content  fat concentrated near body’s CG CG and CB are in line  no rotation about CB

9. RUNNING IN WATER a) feet on floorb) feet do not contact floor

10. Running in Water  often used in therapy or for adaptive groups  shallow water =  buoyancy  load on legs  deep water =  buoyancy   load on legs  does not seem to transfer training effect to land running due to SPECIFICITY in Training

11. HYDRODYNAMIC RESISTIVE FORCES 1. Skin Friction 2. Profile Drag 3. Wave Drag (not found in aerodynamics)

12. Skin Friction  aka Surface Drag  caused by water moving past surface of body   body surface roughness,  with water viscosity   with smooth surface, tight “skin”  least significant Drag Force in swimming

13. Profile Drag (aka Form Drag) Caused by body front edge pushing water apart Caused by body front edge pushing water apart  size of front area =  Drag,  speed =  Drag  size of front area =  Drag,  speed =  Drag Water flow slowed in front   pressure zone Water flow slowed in front   pressure zone Water speeds up in back   pressure zone Water speeds up in back   pressure zone Drag  with streamlining FIG 14.6 on page 461 and FIG 14.7 on page 462 Drag  with streamlining FIG 14.6 on page 461 and FIG 14.7 on page 462

15. Wave Drag ( D wave )  Bow waves act against forward moving body  caused by moving through or near water surface  D wave  with speed of body moving in water  D wave  with up and down motions of the body  Bow wave in Front Crawl allows breathing with reduced profile drag

16. FIG 14.8 WAVE DRAG