Alan Browne wrote:
On 2013.07.03 22:28 , J. Clarke wrote:
In article ,
On 2013.07.03 20:38 , J. Clarke wrote:

The trouble with the metal straps is that things like scooter grabs can
be turned from loss of property into serious injury. With luck it will
be injury of the grabber who gets pulled off the scooter and into the
path of an oncoming lorry. Personally my luck runs more in the
direction of me being pulled into the path of the lorry.

The person on the scooter is in a much more unstable position than a
person walking or standing. OTOH the crafty buggers probably feel the
resistance and abandon within a shake of a lamb's tail.

The scooter's 2 up and gyrostabilized--you've got anywhere from 400-1000
pounds of mass going for you depending on the value of "scooter".

In Asia the people doing the grabbing generally mass about 50 - 60 Kg.
The scooter can keep on going but he's not going with it. And as I
said, as soon as the strap doesn't cut and there is resistance he's just
going to let that one go.

(A pound is not "mass").

The SI unit is the kg. It describes mass, which is both
affected by gravity and has inertia.

In this case, inertia is what is important.

Say the grab happens at 20 km/h speed differential (you walk
briskly at 5 km/s, the scooter is passing you at 25 km/s from
behind), the grabber is not holding on the vehicle or driver
at all, you're 100kg and the grabber is 50 kg.

What happens --- best case for you --- is that you're suddenly
accellerated to 12 km/h and the grabber braked to that speed.
I.e. half your body weight has suddenly slammed into your upper
body from behind, at roughly the speed you'd be able to sprint
(i.e. 100 meters in 14 seconds).

Since you have no chance to react --- you're not even seeing
the grab coming from behind --- you'll be slammed over, your
camera smashed on the ground and your face kissing the concrete
at high speed.


Now imagine what happens if the grabber is seated well, braced
against the impact and holding onto the driver (which again
holds onto the scooter. Guess the effective weight of the
grabber is 3 times his 50 kg. You'll be kissing the asphalt
much faster than Usain Bolt could run into a brick wall if he
wanted to.

You might pull the grabber off the scooter, but you're going to
hospital and your camera will be dead from the impact anyways.

More likely, the grabber will let go as you are yanked forward
and plant your face on the sidewalk and slam your camera down
with you.

-Wolfgang