As the blood falls through the air, it takes the shape of
an oscillating sphere
. The blood droplets will not break up in the air as they fall due to gravitational force alone. Additional forces, however, can break the drops apart.
What shape does a free falling blood drop take?
Unique features of blood as it free-falls includes: → Blood that free-falls through the air has a high surface tension and thus it forms
spherical
droplets as it falls as opposed to the ‘tear-drop’ form that water takes as it falls. Each spherical drop of blood will not break until it hits a surface.
What shape is a drop of blood in the air?
As a blood droplet travels through the air it retains a
spherical shape
due to surface tension. Smaller drops (1mm diameter and less) are almost perfect spheres while larger drops oscillate due a range of other forces acting on the droplet.
What are the three types of blood patterns?
Bloodstains are classified into three basic types:
passive stains, transfer stains and projected or impact stains
.
What causes blood to take that shape during flight?
Passive Bloodstain Patterns. The fluid dynamics of dropping blood are responsible for the stains or patterns produced.
The surface tension of the liquid blood
causes the blood drops produced from a blood source to be spherically shaped.
What two forces act on a falling drop of blood?
In this simple scenario,
gravity and surface tension
play the greatest role. However, keep in mind that other inertial forces will also affect the droplet if the weapon is swung. The droplet will take on a teardrop shape for a very brief moment as gravity overtakes its surface tension.
How fast does free fall travel?
-the ration of the density of blood to the density (mass of the same unit volume) of water. –free falling blood will fall at a
speed of 25.1 plus or minus 0.5 feet per second
. -like all liquids, blood is held together by cohesive force producing a skin like surface resistant to penetration or separation.
What are the 4 types of passive bloodstains?
- Passive Bloodstain. Passive Bloodstain on a rough surface (such as wood or concrete)
- Projected Bloodstain. Projected Bloodstain, possibly a Cast-Off Pattern or a HVIS.
- Transfer Bloodstain.
Does Luminol only show blood?
The reaction is not specific to blood
, however, as other oxidizing agents such as sodium hypoclorite (bleach), certain metals, and plant peroxidases may also cause luminescence with luminol.
What is a passive blood drop?
Passive Drop (Bleeding) — Bloodstain drop(s)
created or formed by the force of gravity acting along
. … Projected Blood Pattern — A bloodstain pattern that is produced by blood released under pressure as opposed to an impact, such as arterial spurting.
What is the fastest that free falling blood can travel?
- Saturation Pattern – Bloodstain pattern resulting from an accumulation liquid on an absorbent material.
- Target – A surface upon which blood has been deposited.
- Terminal Velocity – The greatest speed to which a free falling drop of blood can accelerate in air; This speed is 25.1 ft/sec.
What is a wipe pattern?
A wipe pattern is “
An altered bloodstain pattern resulting from an object moving through a pre-existing wet bloodstain
.”
Is blood spatter analyst real?
A blood spatter analyst, a type of
forensic
science expert, investigates crime scenes and reconstructs crimes based on how bloodstains have formed on various surfaces in order to figure out exactly how a crime was committed.
How is blood evidence detected at a crime scene?
How is blood evidence detected at a crime scene? These tests, referred to as presumptive tests, are used to detect blood at crime scenes
based upon the properties of hemoglobin in the blood
. Further tests at the crime lab can determine if it is human blood or not.
Can you tell how old dried blood is?
Raman spectroscopy and advanced statistics allow the researchers to date a blood stain accurately, provided said blood stain is
less than two years old
. Raman spectroscopy involves shining a laser on a sample and measuring the intensity of scattered light.
What does the shape of an individual drop of blood provide?
Shape of individual drop of blood gives
clues to direction where it originated from
.
