Ram raid granny.

Another of those terrible scooter peoples......


http://news.sky.com/skynews/article/...267255,00.html

[Biker Biggles]

Whi hi.Good to see the Geordie Chapter of the Hells Grannys is still going strong.
Don't mess with em.

Ok, extremely dodgy physics here - I've likely completely misunderstood/forgotten my (now ancient) school lessons.

Mass of granny + scooter (assuming 70kg granny + 180kg scooter) = 250kg
Metric velocity (8mph * 1.609 * 1000 /60 /60) = 3.56 metres per second

Now, I think I've confused acceleration and velocity here, but if not, and if Force = Mass * Acceleration is valid in this instance then force = 1246 Newtons.

Ok, if the force of gravity is taken to be 9.8 metres per second (again, 15 year old school lessons here, memory not what it once was), and our granny/average person has a mass of 70kg still, then the force acting on a 70kg person due to gravity is 686 Newtons.

This is basically a really long winded, complicated, and doubtless completely wrong, way of saying - did those doors break due to the force exerted by gravity upon roughly two average people?

Can you tell there's nothing on TV?

[Biker Biggles]

Remember this was some old boiler from Newcastle so the forces exerted would possibly have needed measuring in megatonnes.
Definition of a Geordie======A Scotsman with his brains bashed out.
So obviously true in this case.

Originally Posted by MiniMatt

Ok, extremely dodgy physics here - I've likely completely misunderstood/forgotten my (now ancient) school lessons.

Mass of granny + scooter (assuming 70kg granny + 180kg scooter) = 250kg
Metric velocity (8mph * 1.609 * 1000 /60 /60) = 3.56 metres per second

Now, I think I've confused acceleration and velocity here, but if not, and if Force = Mass * Acceleration is valid in this instance then force = 1246 Newtons.

Ok, if the force of gravity is taken to be 9.8 metres per second (again, 15 year old school lessons here, memory not what it once was), and our granny/average person has a mass of 70kg still, then the force acting on a 70kg person due to gravity is 686 Newtons.

This is basically a really long winded, complicated, and doubtless completely wrong, way of saying - did those doors break due to the force exerted by gravity upon roughly two average people?

Can you tell there's nothing on TV?

Yep

I'm not sure what physics applies in this situation.
If I had to guess, I think moving objects causing damage is usually analysed in terms of the energy dissipated.
So ke = 0.5 m * v^2 . Using your numbers that gives:
0.5 * 250 * 3.56 * 3.56 = 1584 Joules .
Which doesn't sound like much, but if some small component had to absorb this and couldn't then maybe that's it. From memory, safety toe caps are rated at 200 Joules.

I shouldn't have replied. It'll turn into another torque-power / aircraft lifting off arguments about physics by people who don't really know enough.

The metro isn't exactly the most modern of train systems :P It's absolutely pants. I hate hate hate it with a passion! Cost a bloody fortune, no one else buys a ticket, its slow, in awkward places, and you don't want to travel on it after dark - not that it even runs late. Why does it shut on christmas day/boxing day/new year?! these are the times it needs to run extra trains godammit!

hate hate hate....