Blood Splatter

Blood Splatters taken from rambio2011.wikispaces.com :

Blood Splatter 1

Blood Splatter 2

Blood Splatter 3

Blood Splatter 4

Blood Splatter Pattern from a Laboratory Experiment by Mr Leong TK & Chua HL

What is the shape of the blood splatter?

Round or oval, with different lengths and widths.

Describe any other characteristic of splatter.

The blood splatter is darker in the middle (more concentrated?) and are either irregularly-shaped or elliptical. As the blood is dropped from a greater height, the blood splatter would be more concentrated in the middle. The greater the angle in which the blood is dropped, the greater the length of the blood splatter.

What are the factors that affect the shape of the blood splatter? Name as many as possible.

1) Angle at which blood is dropped.

2) Height at which blood is dropped.

3) Force applied on blood splatter.

4) Amount of blood.

5) Surface which blood is dropped on. 

Generate some hypotheses from the blood splatter patterns observed above.

1) The greater the height at which the blood is dropped, the more concentrated the blood splatter is at the middle. (more blood satellite splatter)

2) The greater the angle of impact of the blood splatter, the greater the length of the blood splatter. (more spread out)

EXPERIMENT 1:

Aim:

To investigate how the diameter of the blood stains vary with height

Results:

Height (cm)	Diameter – A (cm)	Diameter – B (cm)	Average Diameter (cm)
10	1.1	1.0	1.05
30	1.2	1.2	1.20
60	1.3	1.3	1.30
100	1.3	1.4	1.35
150	1.4	1.7	1.55

EXPERIMENT 2:

Aim: 

Investigate how the shape of the blood stains vary with the angle of impact.

Results:

Angle of Impact (degrees)	Width – P (cm)	Length – P (cm)	Width  – Q (cm)	Length – Q (cm)	Average Width (cm)	Average Length (cm)
10	1.4	1.4	1.3	1.4	1.35	1.40
30	1.3	1.5	1.3	1.5	1.30	1.50
50	1.3	1.7	1.3	1.8	1.30	1.75
70	0.7	2.4	0.7	2.5	0.70	2.45

Explanation (from rambio2011.wikispaces.com):

There is arelationship between the length and width of a bloodstain and the angle at which the droplet impacts on a surface. Theangle of impact on a flat surface can be calculated by measuring the length and width of a stain. The angle of impact is the acute angle that is formed between the direction of the blood drop and the surface it strikes. This is an important measure because it is used to determine the area of convergence and the area of origin.

When a droplet of blood impacts a surface at 90°, the bloodstain will be circular. The stain will be more elliptical when the angle of impact increases.