In every volcano disaster movie from Volcano (1997) with Tommy Lee Jones to Dante’s Peak (1997) with Pierce Brosnan someone somewhere tries to out run a lava flow.
Is this possible? (See movie cliché busted by maths here.)
Now a lava flow from Hawaii’s Kilauea volcano is threatening tiny town of Pahoa, Hawaii again. (below).
You will find excellent information about the Kilauea and other volcanoes at the
As the temperature of lava exceeds 10000 C there are very few ways to stop lava. According to the Taylor Kate Brown SMH (10 SEPT 2014) options include:
Bombing
Blasting (it with cold water)
Barricading it
Or adding concrete.
What if you are on your own.
Can you out run lava?
Lets do the maths.
Lava from Kilauea travels 17 yards per hour so the lava velocity is:
One of the greatest dangers in a volcano eruption is not the lava flow OR being hit by a lump of flying lava or rock, but by being choked by the fast moving scorching hot pyroclastic cloud.
In 1991 pyroclastic cloud blew out of the side of Mount Unzen in Japan. NASA has an excellent diagrams for such an event here.
According to the NASA website:
Highly mobile, these flows reach velocities of up to 400 kilometers (250 miles) per hour and can spread as far as 100 kilometers (60 miles) from the eruption point.
Can you out run a pyroclastic cloud?
Here is what happened in 1991 when the pyroclastic cloud blew out of the side of Mount Unzen in Japan.
Here is the sensational pairs team from the 2018 Winter Olympics.
But why do ice skaters spin so fast?
Here is the math!
REASON 1:
Well, mathspiggies, the girl in this video is right. Angular momentum remains constant unless external forces are applied.
L = mvr
L = angular momentum
v = linear velocity
r = separation of object
Louisa Barama, USA
Let’s have a look at this equation:
The fastest spin on ice skates was achieved by Natalia Kanounnikova (Russia) with a maximum rotational velocity of 308 RPM (rotations per minute) at Rockefeller Centre Ice Rink, New York, USA on 27 March 2006. See Guinness Book of Records.
Record spin : vr = 308 RPM
Other spins include:
Mao Asada, Japan, triple Axel
Triple Axel spin vr = 220 – 280 RPM
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Maximum Triple Axel spin vr = 402 RPM
Skaters can spin faster during a triple axel jump because there is no friction from the ice slowing their spin.
To complete a quad axel, it’s estimated that the skater would have to rotate in the air at:
Now, mathspiggies, you must separate Linear Velocity (v1 ) from Angular Velocity (vr ). Linear Velocity is measured in m/sec ie. it is the speed of, say, a skaters foot around the circle. Angular Velocity is measured in either RPM (Revolutions Per Minute) or degrees or Radians per minute. Ie. It is the rate of spin. We can’t judge how many m/sec a skaters foot is moving in a circle. We can only see how fast they spin. In other words, we see their Angular Velocity. When a skaters foot is in the Camel position that foot travels in a very big circle.
But when that same foot is in a Triple Axel postion it moves in a very, very small circle.
Patrick Chan, Canada, Camel Spin
Patrick Chan, Canada, Triple Axel
By halving the radius, firstly, a skater’s Linear Velocity doubles due to the conservation of angular momentum.
Then, secondly, by halving the radius the circumference of the circle moved by , say, the skaters foot is halved.
Overall, by doubling the velocity around the circle and halving the circumference a skater increases their rotational velocity by a factor of 4.
In 2014 Winter Olympics Annette Gerristen (below) lost the Gold Medal in the 1000 m Women’s speed skate competition by 0.02 seconds.
Annette Gerritsen fromthe Netherlands
What are the speed skating times for women?
Women’s Speed Skating Calulations:
Here are the speed calcs for Yara Van Kerkhof of the Netherlands in the 2018 Winter Olympics:
If Yara lost the Gold Medal by 0.02 secs (2 hundredths of a second) what would the distance be between the Gold and Silver place getters?
When 1st and 2nd place are separated by 0.02 seconds, they are travelling at almost the same speed. So the second place contestant is:
23.8 cm behind the Gold Medalist
The 2018 Olympic Gold Medalist in the 500m Women’s Speed Skating was Arianna Fontana.
Italy’s Arianna Fontana wins the 500 m Speed Skating 2018 Olympic Gold Medal in 42.569 seconds ahead of Yara van Kerkhof of the Netherlands and Kim Boutin of Canada.
Men’s Speed Skating:
At longer distances the men’s speed skating speed is similar to the women’s speed above.
If you lose by 0.001 secs…………
Apollo Ono (below) competed in the 1500m men’s speed skating. He has won 8 Olympic Medals.
Sadly, a car has been used as a weapon again in my city, Melbourne.
,…………………………………………..…………………………….
When talking to science types about the Maths of a Car Used as a Weapon they say ‘Yeah! Right! As if you are going to stand around doing the maths when a car is heading towards you!!!!.’……………………
NO!…………………………………………..……..
You don’t do the maths in a crisis. You do it before hand. And it will change your view of car safety for all time.
The reason for waiting until the bear is 15 ft away is to make sure the spray doesn’t disperse in the air. If the Pepper Spray is too spread out it will not stop the bear.
In every volcano disaster movie from Volcano (1997) with Tommy Lee Jones to Dante’s Peak (1997) with Pierce Brosnan someone somewhere tries to out run a lava flow.
