Aim: To investigate how the diameter of the blood stains vary with the height
Apparatus: Retort stand, dropper, metre rule, protractor, clipboard, paper, artificial blood (70ml hot water + 25 g flour + food colouring), newspaper.
Procedure
2. Attach an A4 paper onto the clipboard and place it on the floor.
3. Place the dropper loosely between the clamp on the retort stand 10 cm above the paper as shown. DO NOT SQUEEZE YET !
4. Slowly tighten the clamp to allow only ONE drop of blood to drip onto the paper below.
5. Measure and record the diameter of the blood stain in the table below. (Is one measurement of the diameter enough?)
6. Label the blood stain as “A10”.
7. Repeat Step 4 and 5 to obtain another blood stain on another spot of the paper and label it “B10”.
8. Repeat steps 3 to step 6 by adjusting the vertical distance for 30 cm, 60 cm, 100cm, 150 cm and label them appropriately.
9. Plot a graph of average diameter of blood stain, d against vertical distance, s using "Numbers".
Set-Ups
Vertical Distance of 10cm
Vertical Distance of 30cm
Vertical Distance of 60cm
Vertical Distance of 100cm
Vertical Distance of 150cm
RESULTS Experiment Two
Aim: Investigate how the shape of the blood stains vary with the angle of impact
Procedure:
1. Lay the floor with newspaper to prevent the blood from staining the floor.
2. Attach an A4 paper onto the clipboard andplace it on the floor.
3. Place the dropper loosely between the clamp on the retort stand least 100 cm above the paper as shown. DO NOT SQUEEZE YET !
4. Elevate the clipboard to 10° as shown.
5. Slowly tighten the clamp to allow only ONE drop of blood to drip onto the paper.
6. Measure and record the length, L and width, W of the blood stain in the table below.
7. Label the blood stain as “P10”.
8. Repeat Step 5 and 6 to obtain another blood stain on another spot of the paper and label it “Q10”
9. Repeat steps 4 to step 8 by adjusting the vertical distance for 30°, 50°, 70° and label them appropriately.
