Could a falling cat smash a windscreen?

[Truckosaurus]

Now then.

I found my car this morning with a smashed windscreen.

My home parking space is underneath the windows of several of the flats in my block and it is not unheard of for items to fall out of the window onto the car. A couple of years ago it was a wine bottle, luckily they are much more fragile than car windscreens so it didn't do any damage.

On examining the scene they was no sign of any foreign objects other than a number of hairs/fur around the area and the wing mirror. There was a bemused looking cat sat on the wall of the parking area.

Is it possible that the cat jumped/fell out of a window onto the car? I've heard the urban legend that a cat's terminal velocity is less than their fatal impact speed, so (it is claimed) they can survive falling large distances.

But, I'm not sure a falling cat would contain enough energy to be able to smash a screen.

Any ideas?

[monthefish]

An already-dead cat might just (but very unlikely), an alive cat - no chance.

Could the cat have thrown a brick? (or less sinister, could the cat have been walking along a ledge above your car, and accidntally knocked off a flower pot or something?)

[otolith]

Two cats fighting on car, neighbour throws something, breaks screen?

[DannyVTS]

I wouldn't say so. How much do cats weigh about 5kg? So about the same as a laptop?

I always thought they landed softly and quite elegantly then again

Looking forward to some geeky replies

eta: oops

Edited by DannyVTS on Friday 27th May 10:23

[ikarl]

either way, the cat sounds like a d*ck to me!!!

[Parrot of Doom]

A cat would never make such a jump, unless thrown out. Maybe you've upset a neighbour.

[Mr GrimNasty]

Was the cat wearing a hat? I expect thing 1 or thing 2 actually smashed your car.

[sinizter]

Very unlikely that a normal 'domesticated' feline could smash a windscreen.

[pinchmeimdreamin]

sinizter said:

Very unlikely that a normal 'domesticated' feline could smash a windscreen.

Maybe its a big cat with a goatee.

[Gad-Westy]

Can't see a cat breaking a windscreen myself. They tend to land pretty gently and don't have a sharp edges!

[Rawwr]

Yes.

[Riknos]

ikarl said:

either way, the cat sounds like a d*ck to me!!!

[mrmr96]

DannyVTS said:

I would say so. How much do cats weigh about 5kg? So about the same as a laptop?

I always thought they landed softly and quite elegantly then again

Looking forward to some geeky replies

As stated above, a 'dead weight' would be able to break a screen but an alert cat would not. The reason is the peak force imparted on the screen.

The force required to accelerate (or in this case negativly accelerate) an object is calculated as F=MA, where M is mass in kg and A is acceleration in ms^-2. We'll assume all the objects have the same mass. (brick, dead cat, live cat)

Acceleration is calculated as A=(V2-V1)/t, i.e. change in speed over time.

In this case V2=0 and V1 is assumed to be fixed as velocity of whatever's falling at the point it hits the windscreen. Remember that gravity accelerates all objects at 9.8ms^-2, if we ignore air resistance. This means that all objects can be assumed to hit the windscreen at the same speed if dropped from the same window sill.

So they all weight the same and all hit at the same speed. The result is still differnt though, because the force depends on the time taken to stop the object:

Something like a brick will come to a stop almost immediately, because it's hard and doesn't flex/give at all. i.e. t is small. So this means that the acceleration is a big negative (A=-v1/t). Hence force is also big (F=MA).

Something like a dead cat will stop slower than a brick as it squishes (not nice, but it's how it works). So t (time taken to stop) is bigger, so A is smaller, so F is smaller.

Something like a living cat which lands on it's feet will stop much slower still, as it slows gradually using it's legs to spread the time taken to stop. So t is big, and therefore A is small and hence F is small.

The windscreen will break if F is over a certain threshold. The brick has big F and will break it, the live cat has small F and so won't break it.

HTH

[GadgeS3C]

ikarl said:

either way, the cat sounds like a d*ck to me!!!

Did it quack on impact?

[neilski]

pinchmeimdreamin said:

sinizter said:

Very unlikely that a normal 'domesticated' feline could smash a windscreen.

Maybe its a big powerfully built cat with a goatee.

Fixed that for you.








Is it getting old yet?

[otolith]

pinchmeimdreamin said:

Maybe its a big cat with a goatee.

[thinfourth2]

mrmr96 said:

DannyVTS said:

I would say so. How much do cats weigh about 5kg? So about the same as a laptop?

I always thought they landed softly and quite elegantly then again

Looking forward to some geeky replies

As stated above, a 'dead weight' would be able to break a screen but an alert cat would not. The reason is the peak force imparted on the screen.

The force required to accelerate (or in this case negativly accelerate) an object is calculated as F=MA, where M is mass in kg and A is acceleration in ms^-2. We'll assume all the objects have the same mass. (brick, dead cat, live cat)

Acceleration is calculated as A=(V2-V1)/t, i.e. change in speed over time.

In this case V2=0 and V1 is assumed to be fixed as velocity of whatever's falling at the point it hits the windscreen. Remember that gravity accelerates all objects at 9.8ms^-2, if we ignore air resistance. This means that all objects can be assumed to hit the windscreen at the same speed if dropped from the same window sill.

So they all weight the same and all hit at the same speed. The result is still differnt though, because the force depends on the time taken to stop the object:

Something like a brick will come to a stop almost immediately, because it's hard and doesn't flex/give at all. i.e. t is small. So this means that the acceleration is a big negative (A=-v1/t). Hence force is also big (F=MA).

Something like a dead cat will stop slower than a brick as it squishes (not nice, but it's how it works). So t (time taken to stop) is bigger, so A is smaller, so F is smaller.

Something like a living cat which lands on it's feet will stop much slower still, as it slows gradually using it's legs to spread the time taken to stop. So t is big, and therefore A is small and hence F is small.

The windscreen will break if F is over a certain threshold. The brick has big F and will break it, the live cat has small F and so won't break it.

HTH

Translation

mrmr96 said:

Cats are squishy

[jhfozzy]

thinfourth2 said:

Translation

mrmr96 said:

Cats are squishy

[Pothole]

kids being stupid, took evidence with them?

[jdw1234]

Here you go mate.

You need to get your car fitted with one of these...

http://www.aktivperformanceparts.co.uk/p0/de-cat-p...