2. Movie Stunt Math: Jumping off a Building

October 24, 2018

The main concern when jumping out 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

1 stunt jump from building

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

2 Mathspig Jump off building


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:

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

3 Mathspig stuntman running jump

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. Movie Stunt MATH: The Motorbike Jump

October 23, 2018

Star Stuntman

Picture 2

Star Stuntman 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.”

1. perlin_stunt_ Terminator 3

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.

2 Evel Knievel JUNE-23-1973

His injuries are legendary:

3 the-many-injuries-of-evel-knievel1

More Evel Knievel

Ramp Design

4 Ramp Design Angle of final kicker

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

5 Robbie Maddison's 2008 New Year's Eve jump Arc de Triomphe at the Paris Las Vegas

Picture 2


Moto-X Ramp Jump Maths

The Problem? 

If the ramp angle is too high, the stunt jumper also goes high, but doesn’t travel very far.

If the ramp angle is too low, the stunt jumper doesn’t stay in the air for very long and therefore doesn’t travel far. (see below0

The stunt jumper wants the OPTIMUM RAMP ANGLE.

6 motorbike -parabola Mr Reid



7 bike jump 1 Method 1


Picture 2

Picture 2

As any bike nut knows increasing speed at ake off will increase jump distance.

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

Picture 2


12 optimising ramp angle

Picture 2



13bike jump Method 2

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. 


Why Math Teachers should, um, speak proper!

October 12, 2018

Students can misunderstand teachers.

If math teachers mumble this is the result:

So I’m helping a Year 7 student. Smart kid. This is her test paper. 

NOTE: Students must hear terms clearly pronounced to learn them.


Simple Equation For Calculating Skyscraper Sway in an Earthquake

October 2, 2018

A major and disasterous earthquake has just hit Indonesia. It is the job of engineers to calculate and incorporate – as far as possible- safety margins into the structures of buildings, dams, power plants and even pipe lines. Observers have noted that the skyscrapers in Fukushima wobbled during the recent 8.9 magnitude earthquake in Japan.

This is intentional, as rigid structures can snap in strong winds or during earthquakes.

But the maths used to calculate SKYSCRAPER SWAY is straightforward.

The Earthquake Engineering website offers a simple explanation.

Short, rigid buildings are damaged in earthquakes because they shake very fast. 10 story buildings have a period of oscillation of about 1 second the same as the earthquake pulse. This is VERY dangerous.

Tall, flexible buildings can withstand an earthquake because they can sway. They are like a very large, slow moving tuning fork. If they are TOO RIGID they snap. If they are too flexible the people on the 100th floor would be throw all over the place.

The 59-story steel-construction Citicorp Centre, NY (pictured) has an oscillation time of 6.7 seconds. Details Google Books.

The 102-story brick clad Empire State Empire Building sways about 8cm ( 3 inches) whereas the 110-story steel -mesh World Trades Centre Towers, NY, before they collapsed swayed over 1 m ( 3 ft 5 inches).

One more thing. You want buildings to have springy foundations so they don’t snap at the base and fall over.

Earthquake Engineering

The idea is not to strengthen the building, but to reduce the earthquake generated seismic forces acting upon it. This can be done in 3 ways.

1. Base Isolation. Rubber pads or Rollers. Are used so the base does not feel the full shake or jump off foundations.

Details Base Isolation Specialists

2. Shock absorbers or dampers are added to the structure to dissipate the seismic shock.

Details Damper Supplier


3. Active Tuned Mass Dampers use a computer controlled counter moving weight to actively move against the building sway.

The 508m (1,667-foot) Taipei 101 Tower would sway back and forth up to 60cm (2 feet) each way within five seconds. This according to Wired magazine is highly vomit inducing (barfomatic?).

The Taipei 101 engineers included a 662 tonne (730-ton) counter giant pendulum to act as a counter weight.Some buildings use a big block of concrete.

It is pushed in the opposite direction to the building sway to dampen the oscillation.

Earthquake Engineering Maths

Take 1:

Wired magazine includes the equation for Skyscraper Sway acceleration (See definition of terms @ Wired link):

But I’m going to use a student friendly equation from Wind Engineering for Large Structures.

Calculus Equation here.

Mathspigs, you can just look at this equation and see how to change it to make a building EARTHQUAKE SAFE. Keep in mind that k, the stiffness constant actually decreases for taller buildings.

Imagine you are designing a building to withstand the 8.9 magnitude earthquake. You have already added base isolation. Now you have three options to work with: building mass (m), damping constant (c) and stiffness constant (k). Remember the earthquake force is constant. If you change just the stiffness of the building (k) what happens to the distance of sway(x)?

Engineers have to come up with the optimum design for the strongest structure with least acceleration (but enough building mass for strength), greatest damping and least sway at the lowest cost.


How far does the tallest buidling in the world SWAY in an earthquake?

October 2, 2018

Earthquake Engineering Maths

Take 2:

Structural Engineer Ron Klemencic explained on the Discover News that a simple rule of thumb for calculating skyscraper sway was to simply divide the buildings height in by 500 because the building codes demand the building fit a 1:500 sway ratio.

The tallest building in the world at 2,716 feet (828m), the Burj Khalifa, Dubai, would sway back and forth about 5.5 feet or 1.7 m.

Ahhhhhhhhh!  But you would have to drag Mathspig onto the 168th floor screaming.

But mathspigs you can work out the sway on the top ten tall buildings in the world.


Stunning Art based on Maths

September 29, 2018

Adam R McCausland is a Belfast-based graphic designer whose stunning works incorporate maths themes.

Here is his work (below) titled Fibonacci / Poinsettia

This work (below) is titled: At theHeart of it all. I’ve never seen mirrored Fibonacci curve before. Fascinating. 

What fibonacci art can your class make today?

You can find more of Adam’s inspiring maths art works here.


Trick 1: The Great MATHoudini

September 18, 2018

The Great MATHoudini

Requirements: 1 phone book, Great showmanship

Start by handing one member of the class a sealed envelope. It contains a name that you have seen in your mathematical mind.

All will be revealed at the end of the performance.

Ask one student to write a 3-digit number on the board.

Ask a second student to turn this number around and subtract the smallest number from the largest number.

Ask a third student to turn that number around and add the last two numbers.

Example: N1 = 371.

N2 = 173

N1 – N2 = N3 = 371 – 173 = 198

N4 = 891

N4 – N3 = 891 + 198 = 1089

Give a fourth student a phone book. Ask them to go to page 108 and count down 9 places on the first column and read out the name.

Now open the envelope.

Da! Da!


How does it work? The numbers ALWAYS add up to 1089 so you had plenty of time to check out the name in the phone book.

Source: Magic/Menatalism Tips and Tricks