## Can you escape a FALLING TREE?

August 24, 2019

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.

May 14, 2019

# Grizzly Bear

Weight:  550 lb

Height:  8’ 2”

Top Speed: 35 mph  =   51 ft/s

# Brown Bear

Weight:  1,500 lb

Height:  8’ 2”

Top Speed: 22 mph  =  32 ft/s

Comparing these speeds to the fastest man on earth, Usain Bolt:

## Usain Bolt:

Top speed: 27 mph  =   40 ft/s

# Bears are not dangerous:

………………………………………………………………………

In fact, more Americans die each year from choking on their own vomit than are killed by bears.

More death stats here

Nevertheless, bears are very fast. So you can see why Park Rangers offer the following advice:

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.

July 17, 2017

# Grizzly Bear

Weight:  550 lb

Height:  8’ 2”

Top Speed: 35 mph  =   51 ft/s

# Brown Bear

Weight:  1,500 lb

Height:  8’ 2”

Top Speed: 22 mph  =  32 ft/s

Comparing these speeds to the fastest man on earth, Usain Bolt:

## Usain Bolt:

Top speed: 27 mph  =   40 ft/s

# Bears are not dangerous:

………………………………………………………………………

In fact, more Americans die each year from choking on their own vomit than are killed by bears.

More death stats here

Nevertheless, bears are very fast. So you can see why Park Rangers offer the following advice: