Squirrels can survive a fall from any height, at least hypothetically (McGill OSS)

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Squirrels, in theory, can survive a fall from an object of any height due to two factors: their size and their mass. A force (such as the force of gravity) is calculated by multiplying mass and acceleration. The acceleration due to gravity on Earth is always roughly 9.81 m/s2, regardless of what object it is acting on. Squirrels are not very heavy—a grey squirrel only weighs about 0.5 kg—meaning that the force acting on a falling squirrel just isn’t that big.

Force = mass*acceleration = 0.5 kg * 9.81 m/s2 = 4.9 N

We measure forces in a unit called “Newtons”, named for Isaac Newton who gave us Newton’s three laws of motion.

Compare this to, for example, a falling 60 kg human, which would be pulled downward with a force of about 489 N. A factor of 100 higher!

On top of being small, squirrels are fluffy and intuitively spread their bodies out when falling. This allows them to experience as much wind resistance as possible, slowing down their rate of descent. Some squirrels even use this fact to glide through the air. While gliding is not the same as flight, we nonetheless call them flying squirrels.

For these two reasons, the terminal velocity (fastest speed while falling) of squirrels is slow enough that they will, at least in principle, never fall so hard that they hurt themselves.

This article was originally posted here: https://www.mcgill.ca/oss/article/did-you-know/squirrels-can-survive-fall-any-height-least-hypothetically

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Rats Don’t Really Squeak (McGill OSS)

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Originally posted here: https://www.mcgill.ca/oss/article/did-you-know-general-science/rats-dont-really-squeak

Despite what movies would have you think, rats barely ever make any sounds, at least those that humans are able to hear. Rat’s vocalizations start at around 2 kHz and extend as far up as 100 kHz. For reference, human’s can hear roughly 2-20 kHz, so the vast majority of rat noises made are well into the ultrasonic spectrum. Pet and wild rats alike will seem almost mute, unless put into extreme distress, when they will squeak or shriek audibly. If you record rats with an ultrasonic microphone however, you find that they actually make many noises, to convey everything from joy to dominance and even to laugh!

Lies of Leaping Lemmings

Originally published here: https://mcgill.ca/oss/article/did-you-know-history/lies-leaping-lemmings

You’ve likely heard phrases like ‘don’t be a lemming’, or your run of the mill internet troll scream-typing about how we’re all following our governments ‘like lemmings, over the cliff to our doom!’ What you might not know though is that the idea of the suicidal lemmings is a completely fabricated oneLemmings do not jump to their doom off of cliffs.

Lemmings have often been the subject of bizarre beliefs. A 1530 geographer, Zeigler of Strasbourg, theorizing that lemmings literally fell out of the sky and into existence during stormy weather, a theory he picked up from Alaskan native peoples the Yupik and Iñupiat. It wasn’t until the 1700’s that Carl Linnaeus proved lemmings had a natural origin. In 1958 however, Disney reignited the mystery around lemmings with their documentary White Wilderness. A scene in the film (click here to watch it) shows lemmings hurling themselves off of a cliff into the sea, seemingly drawn by some unknown force. This famously successful film won an academy award and is almost solely responsible for the creation of the suicidal lemming belief. However, in a 1982 CBC investigation revealed that

1. No lemmings are found natively where the documentary was filmed, because

2. White Wilderness was filmed in land-locked Alberta, not on the Arctic Ocean, so to get around it, Disney

3. Purchased a few dozen lemmings from Inuit children and herded them over a snow-covered lazy-Susan and into a river.

So how did Disney come up with the idea to murder some lemmings for a film? Well, lemmings, like other rodents, do reproduce rapidly and experience great population booms, and when a population at a location gets too massive, they will disperse from the site, so if an observer was monitoring only 1 location, they may see what seems to be a mass, unexplained death. Disney did get 2 things right at least, lemmings do not hibernate, and they do swim, though much better than is implied in White Wilderness.