First of the Day Blood Spatter Lab Blood
First of the Day….
Blood Spatter Lab Blood spatter from a sneeze from a bloody nose
“Remember… it’s blood ‘Spatter’ not blood Sp. Latter. ”
Blood Drop blood spatter animations
Eccentricity: of an ellipse is the ratio of the distance between the foci to the length of the major axis; this is necessarily between 0 and 1. If the ellipse has the Cartesian equation
Basically “eccentricity” is how “oval” and ellipse is…. Which one is most “eccentric? ”
Measuring the shape of the blood drops
Impact angle = sin-1(arcsin) width (d) length (D)
drop on left: W = 1. 8 cm L = 2. 8 cm Impact angle = sin-1 (arcsin) width length Do first = sin-1 (arcsin) 1. 8 cm 2. 8 cm = sin-1 (arcsin) (0. 643) = 40 degrees 0. 64285714….
0. 64285714….
drop on right: W = 1. 2 cm L = 5. 23 cm Impact angle = sin-1 (arcsin) width length = sin-1 (arcsin) 1. 2 cm 5. 23 cm = sin-1 (arcsin) (0. 229) = 13 degrees
Formula for Table 1 Angle of Impact Lab Impact angle = sin-1(arcsin) width length ¼” = one foot on diagram on your answer sheet Formula for Table 2 Height above point of target XY = tan(i) x XJ, angle i being the angle of impact from the previous data table
Blood Spatter Alteration of bloodstain over time • Blood dries and clots over time. • Difficult to estimate the time the blood exited the body. • Clotted smears can indicate time of movement
Blood Spatter Determining Direction of Blood • The angle can be determined mathematically. • Width/Length, then take the inverse sin (sin-1). • This number is the impact angle (90 = perpendicular to surface; <10 at a sharp angle)
- Slides: 24