Ball Watches - Shock resistance

[GBGaffer]

I noticed an ad for the above mentioned brand which claimed a shock resistance of 5,000 G - can this be true, and moreover what's the point as I would have thought the wearer would have been past caring!

Cheers for some insight

G

[LukeBird]

Was looking at the Omega site the other day and (just double checked!) their watches are shock resistant to 5000G.
It's much like their depth ratings, pointless to a person, but if they're built beyond typical 'everyday' use (I for instance don't have a bath that is 300m deep! ) they are far less likely to be damaged and/or fail in those situations.

[andy_s]

5,000G?! That sounds impressive - is that a particular model or the whole range? Is that 5,000G without breaking or 5,000G without the movement breaking/timekeeping being affected...?

[TheEnd]

Remember 5000G comes along pretty quick when a watch hits a hard surface and stops instantaneously.

[ShadownINja]

TheEnd said:

Remember 5000G comes along pretty quick when a watch hits a hard surface and stops instantaneously.

Indeed. It's simply deceleration. 5000 x 9.81m/s/s. What's the deceleration when a watch falls 1 metre and lands on concrete? Anyone care to calculate? I tried but there's a lot of guesswork in terms of how quickly it takes to fall plus when it's travelling at full speed when it reaches ground level and then one has to assume the movement travels maybe 1mm inside the case before coming to a complete stop.

[mrfunex]

Ok, so assuming you drop the watch from 1 meter, and it encounters no air resistance;

v = Final velocity
u = Original velocity = 0 m/s
a = Acceleration = 9.81 m/s/s
s = Distance = 1m

So the speed the watch will hit the ground is given by;

v^2 = u^2 + 2 a s
v^2 = 0 + 2 x 9.81 x 1
v = 4.42 m/s

Now, assuming as we are, that the watch hits a hard surface and comes to a stop within 1mm, using the same formula;

v^2 = u^2 + 2 a s
0 = 4.42^2 + 2 x a x 0.001
a = 9810 m/s/s
a = 1000g

If your watch can sustain 5000g without breaking, that means that you can drop it from a height of 5m, assuming linear acceleration and it will hit the ground at 9.90m/s. Of course, if you drop your watch onto something harder, or it bounces, the acceleration on the watch will be a LOT more.

Conclusion: Don't drop expensive watches onto concrete surfaces!

[ShadownINja]

Thanks. I thought that was how to calculate it but I'd just woken up at the time.

[mrfunex]

Hope my maths is correct!

[ShadownINja]

Looks like it is without getting out paper and checking properly.

[andy_s]

I think the DIN standard for saying a watch is shockproof means the watch is tested by hitting it twice in different places with a plastic hammer at 4/5m/s to simulate being dropped 1m onto a wooden floor. It then can't deviate more than 60' in the next 24hrs.

There's a video of a G-Shock being used as a hockey-puck, hence the name I guess.

[ShadownINja]

I think Casio takes it to a whole new level.

http://www.youtube.com/watch?v=VSaciL-tNg8

[LukeBird]

mrfunex said:

Hope my maths is correct!

Bored were you chap!

I'll make sure I never chuck my watch more than 4.5m into the air!