Characteristics of liquid blood(Slide 2) Specific gravity,
Surface Tension (slide 3): is a characteristic of liquids whereby they are resistant to penetration or separation. The surface acts to reduce surface area. A small mass of liquid which becomes detached becomes rounded into a sphere; the shape gives the minimum service area for any given volume; a falling blood drop is not tear-drop shaped.
For instance, blood flowing downwards towards the fingertips from a cut on the hand accumulates on the fingertip and increases in volume until the gravitational pull (its weight) exceeds surface tension (slide 4). Such droplets will have a fairly uniform of volume of 50 ml (0.05 ml). More rapid bleeding may result in slightly larger drops but slower bleeding does not result in smaller drops. Blood cast from a moving source will tend to consist of smaller droplets (slide 5) Blood behaves as a projectile in motion and obeys the laws of physics and mathematics.