Have Yourself a Mathsy Little Christmas

…no-1………..no-2…….no-3….no-4….no-5………..

It is Xmas … Ah! The Joy of Algebra!

Great Math Xmas Ornament Ideas for Middle School here @ MathEqualsLove blog.

Mathematicians can make mountains out of mince pies, but in this case Dr Eugenia Cheng, who is Professor of Pure Mathematics at the University of Sheffield, UK, makes it look fun. The video clip includes some great Middle School Maths that you can eat.

Braindead Math for Halloween

Tarantino, being a connoisseur of Fake Blood, used several types of Fake Blood in the film Kill Bill II ranging from good splatter to free-flowing blood. According to one fanzine, in this film, Uma Thurman killed 88 opponents with a sword.  So the numbers(above)are in the right ‘blood-soaked’ ballpark. More survival math (The Hunger Games) here.

2. Stuntman Math: Jumping off a Building

This is a repost of Mathspig’s very popular Stuntman/woman series.

The main concern when jumping off a building is that the airbag (cardboard boxes) cover the drop zone.

The maths calculations involved in jumping off a building are straightforward. You might like to check out How Maths Solved a real murder.

Jump Height that Kills

It doesn’t take much of a fall to cause damage. Sean Hughes, professor of surgery at Imperial College, London. Says “From a height of 3m you could fracture your spine,” he says. “At around 10m, you’re looking at very serious injuries.” (The Guardian, 20 MAY 2014)

Stunt Jump from building from standing start

As this jump – as in most base jumps – involves a standing start:

Airbagsupplies.

Stunt jump from building running

We will assume you are no Usain Bolt. His running speed, the fastest in the world, is 44.72 km/h (12.42m/s, 27.44 mph).

We’ll say your running speed on take-off is:

V_y = 15 mph = 24.1 kph = 6.7 m/sec

Don’t do this at home.

NB: Airbag dimensions: 20m x 20m x 4 m

Handstand of death

Would you jump off a 25 story building?

 

3. STUNTMAN MATH: Motorbike Jump

This is a repost of Mathspig’s very popular Stuntman/woman series.

Star Stuntmen

Star Stuntmen Monte Perin (pictured) has involved many films, including “Spider-Man,” “Star Trek, “Indiana Jones and the Kingdom of the Crystal Skull” and portraying Arnold Schwarzenegger’s stunt double in “Terminator 3: Rise of the Machines.”

Perhaps his most difficult stunt was landing his Harley in an open boxcar of a moving train for Disney’s 2008 Adam Sandler movie “Bedtime Stories”. In a career of over 25 years Perin has broken “almost everything” including both his arms, legs, knees, feet, ankles, several ribs, his back and his pelvis. See Confessions of a stuntman

Veteran stuntman Evel Knievel (1938 – 2007) was the pioneer of many stunt jumps. Here he is jumping 10 cars and 3 vans in 1973.

His injuries are legendary:

More Evel Knievel

Ramp Design

The angle of the kicker in ramp design can vary from 10⁰ – 70⁰ (See below)

 

Moto-X Ramp Jump Maths

 

 

 

As any bike nut knows increasing speed and angle of take off will increase jump distance.

Here is a graph from final gear for speed vs angle to jump 90m.

 

METHOD 1 is approximate (See STEP 1 & STEP 2 above), but as METHOD 2 produces the same ans (See above), it is very useful.

You will find a thoroughly detailed calc for STUNT JUMP MATHS here:

And everything you ever wanted to know about PHYSICS OF STUNT JUMPS here. 

Can you escape a FALLING TREE?

Tragically, 5 people have been killed by falling trees in Victoria, Australia, this Winter. 

In 3 separate accidents, 4 died when trees crushed the occupants in cars. One victim was a pedestrian.

So if you were walking through a park could you escape a falling tree if you either heard a cracking sound or saw the tree starting to fall?

With thanks to Physics Stack Exchange.

For an inverted pendulum near the top of its arc, there is no period, but the quantity √ℎ/𝑔 does represent a characteristic time scale for this system. The tree will take a few of these characteristic times to fall.

Mathspig hates seeing an old tree felled, but it does give us the necessary time data.

 

There are many assumptions in these calculations.

*You’d be hit by the tree trunk, not a branch which would hit you sooner.

*There is no wind pushing the tree over.

*The tree falling is an approx to a reverse pendulum.

 

Eat Red Meat and Die ….. NOT NOW! ….. Maybe, sometime.

Here we go again.

“Eating even the moderate amounts of red and processed meat sanctioned by government guidelines increases the likelihood of developing bowel cancer” according to the above article in The Guardian, UK.

The sample size was 500,000. That’s good. It is a self-selecting sample. That’s not good. They could all be health fanatics. But here is the kicker:

“The researchers found those who ate the most and least red and processed meat tended to exaggerate their consumption or lack thereof.”

That’s a shock. People lie or exaggerate. Even the researchers then suggest – despite the screaming headline – that you don’t change your diet.

Although, looking at the plate above … I would!

Real Men Eat Red Meat and Die … Sometime!

According to this headline in THE AUSTRALIAN 25th, March 2009   meat eaters are at risk of dying of cancer. The study published in  Archives of Internal Medicine involved half a million people over 10 years. So far so good. That is a good sample size. The sample consisted of people aged 50 to 71 years at baseline or, obviously, after 10 years 60 to 81years!!!!  So some deaths would be expected. Nevertheless, the article states: 

“Men whose red meat intake put them in the top 20 percent consumption band were 22 percent more likely to die of cancer in the 10 years of the study, compared to men whose intake was in the lowest 20 percent. For women, there was a 20 percent increase in risk.”

Here is the problem. Firstly and I quote from the original study: “Meat intake was estimated from a food frequency questionnaire administered at baseline.’ So they asked people once what their eating habits were then assumed they continued for the next 10 YEARS??? How likely are your eating habits to change in 10 years???

Secondly, and this was mentioned in the article without explaining the maths, big meat eaters tend also to be big drinkers, smokers, obese and the rest. This study has tried to separate out meat eating from other unhealthy lifestyle choices using the Cox Regression. Mathematical wizardry has produced these numbers but they don’t mean much. 

If the study used a control group of drinking, smoking, obese vegans then compared mortality rates over 10 years that would be interesting. But where do you find half a million of them???????? 

Finally,  the study  concluded ‘Red and processed meat intakes were associated with modest increases in total mortality, cancer mortality, and cardiovascular disease mortality.’ Not the stuff of headlines at all!!!!!!!