<VV> VirtualVairs Digest, Vol 187, Issue 29

[William Hubbell]

Bah!  Newtonian physics!!  Relatively speaking, acceleration means any change in velocity.

“Any change in the velocity of an object results in an acceleration: increasing speed (what people usually mean when they say acceleration), decreasing speed (also called deceleration or retardation), or changing direction (called centripetal acceleration). Yes, that's right, a change in the direction of motion results in an acceleration even if the moving object neither sped up nor slowed down. That's because acceleration depends on the change in velocity and velocity is a vector quantity — one with both magnitude and direction. Thus, a falling apple accelerates, a car stopping at a traffic light accelerates, and an orbiting planet accelerates. Acceleration occurs anytime an object's speed increases or decreases, or it changes direction.”

Bill

On Aug 16, 2020, at 12:56 AM, FrankDuVal <corvairduval at cox.net> wrote:

Um, by definition, positive acceleration in a different direction is deceleration!  F=MA  -F=M (-A)

Frank DuVal

And to think last week I thought VV was broken as there were no posts for several days....


> On 8/15/2020 9:46 PM, William Hubbell wrote:
> It’s only negative based on a particular frame of reference.   If your frame of reference is something fixed outside of your vehicle, then, yes, it is negative.  But based on yourself as the frame of reference, it is simply positive acceleration in a different direction.
> 
> Bill
> 
> On Aug 15, 2020, at 9:42 PM, FrankDuVal via VirtualVairs <virtualvairs at corvair.org> wrote:
> 
> That's negative acceleration, since the change in velocity is negative. i.e. 60 to 0 MPH, hitting bridge abutment at speed.
> 
> in English, Deceleration is the term we use.
> 
> Sudden Deceleration kills.;-)
> 
> Frank DuVal
> 
>>> On 8/14/2020 4:21 PM, William Hubbell via VirtualVairs wrote:
>> Technically speaking, it’s sudden acceleration that kills (acceleration defined as change in velocity) - sudden stopping being really just sudden acceleration in the opposite direction of travel.
>> 
>> Bill
>> 
>>> On Aug 14, 2020, at 2:10 PM, James P. Rice via VirtualVairs <virtualvairs at corvair.org> wrote:
>> 
>> All:  Speed does not kill.  Sudden stops kill.  Moral:  Avoid situations
>> which result is sudden stops.