[Lex Computer & Tech Group/LCTG] Here is something I never knew. From an email I get

Larry Wittig t.light at verizon.net
Wed Jan 20 15:47:29 PST 2021


Don't confuse the longitudinal wave speed with the bending wave speed.  
If the bat was being used like a pool stick the longitydinal wave spped 
would apply.

-- Larry

On 1/20/21 9:45 AM, Steve Isenberg wrote:
> Speed of sound in steel is 5,960 m/s (not km/s).
> Or so I hear.
> -steve
>
> On Wed, Jan 20, 2021 at 9:26 AM john rudy <jjrudy1 at comcast.net> wrote:
>
>> If I have a solid object which is 1 light year long and I push it and there
>> is somebody else on the other end, how long would it take for them to
>> notice
>> that I pushed it?
>>
>> When you push on an object - even one that appears completely solid - the
>> movement takes time to move through the object. In pushing on the object,
>> you're actually generating a wave that propagates through the object, as
>> atoms push on adjacent atoms. When a baseball player begins to swing a bat,
>> the far end of the bat actually lags behind the near end of the bat. The
>> length of the bat is short compared to the speed at which the effect
>> propagates through the bat, so it appears to be completely rigid. But the
>> longer the object, the more noticeable it will be that the force takes time
>> to move through the object.
>>
>> And how fast does the force move through the object? At the speed of sound.
>>
>> And how fast is that? Depends on the substance. Suppose the solid object is
>> made of steel. Movement would propagate through the object at 5.960
>> km/second. So if you had a steel object that was a bit less than 6 km long
>> and you push on one end, someone on the other end would feel the effect 1
>> second later.
>>
>> If you had steel rod that was one light-year in length, a force would take
>> a
>> little over 50,000 years to propagate to the other end.
>>
>>
>>
>>
>>
>> John Rudy
>>
>> 781-861-0402
>>
>> 781-718-8334 (cell)
>>
>> John.rudy at alum.mit.edu <mailto:John.rudy at alum.mit.edu>
>>
>>
>>
>> 13 Hawthorne Lane
>>
>> Bedford, MA  01730-1047
>>
>>
>>
>>
>>
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