Posts Tagged ‘Hunger Games Blood’


Hunger Game: Survival Maths 1

April 11, 2012

How long can you live if you are bleeding?

Unlike Kill Bill where Tarantino used, literally, hundreds of litres of fake blood (See Mathspig Post: Don’t Bleed Your Fake Blood on Me), The Hunger Games shows very little blood.

Nevertheless 11 tributes are killed violently in the first few minutes of the game and Peeta is wounded later in the movie(pic with Katniss above).

To calculate how long you would last in The Hunger Games if bleeding we must know your volume of blood and the rate of bleeding.

1. How much blood do you have?

According to the BJA, the British Journal of Anaesthesia, blood volume is  7% of body weight in adults and 8 – 9 % of body weight in children.  Doctors are not confusing weight and volume. Blood is very close to the density of water and so 1 litre of blood weighs 1 kg. 

(NB: Future Engineers: Blood does not flow like water as the blood platelets affect the viscosity.)

Using blood volume (in litres) as 8% of body weight (in kg) then typical blood volumes for teenagers would be:

Age Group





Blood Volume


















2. How long would you last if bleeding?


Obviously, it will depend on the rate of bleeding.

According to the BJA massive blood loss equals a blood loss rate of 150ml/min or 50% of blood volume loss within 3 hrs.


B = total blood loss ml

R = rate blood loss in ml/ min = 150 ml / min

t = time min

B = Rt

B = 150 t

According to New Scientist loss of blood IN THE AVERAGE ADULT produces the following symptoms:

A  750 ml: feel blood loss

B  1500: weak, thirsty & anxious

C  2000 ml : dizzy, unconscious

D  3000 ml: Dead

See A, B, C and D on graph below.

3. How long have you got?

First, calculate  50% of your blood volume for your age.

Now go to the blood loss graph and see how long it would take you to lose this volume.

You can stop doing the maths now, mathspiggies, and get some help to stop the bleeding.


Hunger Games : Survival Maths 2

April 11, 2012

Katniss’ weapon of choice is the bow and arrow.

Mathspig noticed in the film that Katniss was aiming the arrow directly at the target. This is a problem. Arrows drop under gravity. If Katniss aims directly at the target she will hit it below her aim point. To overcome this she must raise her arrow aim.

What angle should she choose?

Robin Hood used a long bow and in the film Robin Hood archers raised their bows at a very high angle to cover long distances. See the diagrams below from Robin Hood Give Us Your Best Shot

 According to The Flaming Arrow the speed of a modern arrow is 100 m/sec with a 65 lb draw weight.

Mathspig believes in using the SIMPLEST maths solution. In this case, very short arrow flight times are involved. 

So we will assume the arrow velocity (Va) equals horizontal vector speed (Vx). This is an approximation that makes the maths sweet. Such an approximation might work for the arow flight in the first diagram (above), but not in the second.

First, mathspigs, we’ll calculate the arrow flight time to a target 100m away and then we will calculate the distance the arrow would drop vertically in that time as this will tell us the point in the air where Katniss should aim.

 NB: An arrow will drop 4.9m over 100m to the target. In other words, Katniss would miss a human completely if she did not allow for gravity. Experienced archers automatically make this adjustment to their aim.

Gravity Eqn in the graph above comes from School for Champions