Blood Spatter Lab

Blood Spatter Lab Blood spatter from a sneeze from a bloody nose

Remember its blood Spatter not

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 = sin-1 (arcsin) 1.8 cm 2.8 cm

= sin-1 (arcsin) (0.643) = 40 degrees 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 Formula for Table 1 Angle of Impact

Impact angle = sin-1(arcsin) width length = 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)