## Posts Tagged ‘geometry’

## Math Joke 4: Geometry

February 18, 2019## Why Math Teachers should, um, speak proper!

October 12, 2018## Mad Mince Pie Maths

December 13, 2016**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.**

## Smoke Jumpers and their Amazing Wildfire Maths . . . . . . . . . . . . . . METRIC UNITS

December 5, 2016

With wildfires in Texas and now Australia is facing the fire season, it is time to think about fire fighter maths.

# METRIC UNITS

**Background Story**

On **5 ^{th} August 1949 Wag Dodge** was dropped by parachute with 14 other fire fighters into Mann Gulch, a steep-sided gully in a Montana pine forest. Fire fighters who parachute in to put out small blazes started by lightening are called Smoke Jumpers. As they worked their way down the sides of the gully the breeze was blowing away from them. But the wind soon shifted. This produced an updraft, which increases the speed of the fire front. The 15 Smoke Jumpers turned and started running for their lives uphill.

# HOW FAST CAN YOU RUN?

# METRIC UNITS

## Time Trial:

Mark out a 10 m course. Make 3 time trials.

t_{1 }=

t_{2} =

t_{3}=

Average your time:

t_{av} = (t_{1 } + t_{2} + t_{3)}/ 3 =

Your Speed S = 10/t_{av} = ……… m/sec

## HOW FAST IS A GRASS FIRE?

This will, of course, vary depending on the wind speed. A typical grass fire in Australia in a flat area can travel at **20kph** (up to 30 kph) in a gentle breeze.

Fire Front Speed Grass Fire

Fire Front Speed = 20 kph = 20 x1000/(60 x 60)

= 20 x 0.27777777 = 20 x 0.28 m/sec

= 5.6 m/sec

# CAN YOU OUT RUN A FIRE?

__Average Running Speed Boy__ 13–14 yo = 3.0 m/sec

__Average Running Speed Girl__ 13–14 yo = 2.4 m/sec

We’ll assume, boy or girl, that you are really motivated and can run away from the fire at top speed of 3.0 m/sec. Now calculate the distance you can run and the fire front moves in 10 secs intervals up to 1 minute.

This is not looking good. See more Firefighters Need Maths **here**.

We can do very accurate calculations using simultaneous equations.** Wildfire Algebra**: Detailed Worksheet using simultaneous equations and solutions **here**.

# NOW YOU ARE RUNNING UP HILL. WHAT HAPPENS?

We’ll assume, due to being motivated by having a fire licking your heels, that you can run at your top speed up hill for a short time, at least. But here is the problem.

Heat rises and so there is a Chimney Effect pushing the fire uphill. The rule of thumb used by fire fighters is:

Each 10º increase in slope, the **fire front speed doubles**.

Now you can calculate the distance travelled by the fire front up a slope at a 30º angle.

Don’t forget you can use the WEB 2.0 Calculator **here**.

Even at your top running speed, which is unlikely up a slope, you can run 180 m in 1 minute. In that time the forefront has moved 2688 m or 2.7 km.

It depends how far away you are from the fire front, but it seems you cannot out run this fire front.

Again we can do very accurate calculations using simultaneous equations.

See Firefighters Need Maths **here**.

Wildfire Algebra: Worksheet and solutions **here**.

# CAN YOU OUT RUN A WILD FIRE?

High winds can turn a bush or forrest fire into a WILD FIRE with wind speeds up to 110 kph and temperatures up to 2000 °C, which can and does melt glass and cars.

The fire front speed doubles with every 10º, so speeds for the fire front can reach 220 kph, 330kph and up to 550kph.

# What happened to the Smoke Jumpers?

When the fire front changed direction Wag Dodge and 14 other Smoke Jumpers found themselves running for their lives up a steep slope. What did Wag do next?

ANS: Here’s the amazing thing. Wag realised he could not out run the fire at that point. So he stopped. Took off his back pack. Took out some MATCHES and lit a fire in the grassy patch in front of him. Just before the firewall hit he threw himself face down on the burnt patch. He survived. The other 14 firefighters did not.

## Smoke Jumpers and their Amazing Wildfire Maths . . . . . . . . . . . . . . USA UNITS

December 5, 2016

With wildfires in Texas and now Australia is facing the fire season, it is time to think about fire fighter maths.

# USA UNITS

**Background Story**

On **5 ^{th} August 1949 Wag Dodge** was dropped by parachute with 14 other fire fighters into Mann Gulch, a steep-sided gully in a Montana pine forest. Fire fighters who parachute in to put out small blazes started by lightening are called Smoke Jumpers. As they worked their way down the sides of the gully the breeze was blowing away from them. But the wind soon shifted. This produced an updraft, which increases the speed of the fire front. The 15 Smoke Jumpers turned and started running for their lives uphill.

# HOW FAST CAN YOU RUN?

# USA UNITS

## Time Trial:

Mark out a 30ft course. Make 3 time trials.

t_{1 }=

t_{2} =

t_{3}=

Average your time:

t_{av} = (t_{1 } + t_{2} + t_{3)}/ 3 =

Your Speed S = 30/t_{av} ft/sec

# HOW FAST IS A GRASS FIRE?

This will, of course, vary depending on the wind speed. A typical grass fire in Australia in a flat area can travel at **12mph** (up to 20mph) in a gentle breeze.

Fire Front Speed Grass Fire

Fire Front Speed = 12 mph = 12 x 5280/(60 x 60)

= 17.6 ft/sec

= 18 ft/sec

# CAN YOU OUT RUN A FIRE?

__Average Running Speed Boy__ 13–14 yo = 10 ft/sec

__Average Running Speed Girl__ 13–14 yo = 8 ft/sec

We’ll assume, boy or girl, that you are really motivated and can run away from the fire at top speed of 10 ft/sec and -Wow! – this is easy math. Now calculate the distance you can run and the fire front moves in 10 secs intervals up to 1 minute.

This is not looking good. See more Firefighters Need Maths **here**.

We can do very accurate calculations using simultaneous equations.** Wildfire Algebra**: Detailed Worksheet using simultaneous equations and solutions **here**.

# NOW YOU ARE RUNNING UP HILL. WHAT HAPPENS?

We’ll assume, due to being motivated by having a fire licking your heels, that you can run at your top speed up hill for a short time, at least. But here is the problem.

Heat rises and so there is a Chimney Effect pushing the fire uphill. The rule of thumb used by fire fighters is:

Each 10º increase in slope, the **fire front speed** doubles.

Now you can calculate the distance travelled up a slope at a 30º angle.

Don’t forget you can use the WEB 2.0 Calculator **here**

Even at your top running speed, which is unlikely up a slope, you can run 1080 ft in 1 minute. In that time the forefront has moved 8640 ft or 1.6 miles. It depends how far away you are from the fire front when you start running, but it seems likely that you cannot out run this fire front.

Again we can do very accurate calculations using simultaneous equations.

See Firefighters Need Maths **here**.

Wildfire Algebra Worksheet and solutions **here**.

# CAN YOU OUT RUN A WILD FIRE?

High winds can turn a bush or forrest fire into a WILD FIRE with wind speeds up to 70 mph and temperatures up to 2000 °C, which can and does melt glass and cars.

The fire front speed doubles with every 10º, so speeds for the fire front in a strong wind can reach 140 mph, 210 mph and up to 280 mph.

# What happened to the Smoke Jumpers?

When the fire front changed direction Wag Dodge and 14 other Smoke Jumpers found themselves running for their lives up a steep slope. What did Wag do next?

ANS: Here’s the amazing thing. Wag realised he could not out run the fire at that point. So he stopped. Took off his back pack. Took out some MATCHES and lit a fire in the grassy patch in front of him. Just before the firewall hit he threw himself face down on the burnt patch. He survived. The other 14 firefighters did not.

## MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig MathsPig …………………………………………………. with Kerry Cue

March 1, 2016

#### Hellooooooooo My Sweet Little Picassos,

#### Mathspig has gone, like, totally Cubist this month. You too can turn any portrait of yourself into a Cubist Master piece (See Mathspig portrait above), here.

**Mathspigs maths friends, Lyn and Erwin, who I met at the 13e Salon Culture & Jeux Mathematique, Paris, have sent me a reminder about their amazing Cryptocube construction kit (Mathspig is twirling one above) . This is not for the faint hearted. It’s a Big Maths challenge, but well worth the investment especially for schools. You can learn more about the Zometool Cryptocube construction kit here.**

**Meanwhile, here are links to 10 Amazing Ways to See a Cube:**

## 1. Tube Cube

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

## 2. Folded Paper Cube

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

## 3. Anamorphic Cube

>>>>>>>>>>>>>>>>>>>>>>>>

## 4. Floating Cube

>>>>>>>>>>>>>>>>>>>>>>>>

## 5. Street Art Cube

>>>>>>>>>>>>>>>>>>>>>>>>

## 6. EDIBLE CUBE

>>>>>>>>>>>>>>>>>>>>>>>>

## 7. GIANT CUBE

>>>>>>>>>>>>>>>>>>>>>>>>

## 8. Spaghetti Cube

>>>>>>>>>>>>>>>>>>>>>>>>

## 9. Fashion Cube

>>>>>>>>>>>>>>>>>>>>>>>>

## 10. CUBIC BUBBLE

#### …………………………………………………………….

#### Toodles

### …………………………………………………….

## Mathspig

## 4. Floating Cube

February 9, 2016## ……………………