ed9048e5   
   From: relativity@paulba.no   
      
   Den 30.01.2026 15:59, skrev Maciej Woźniak:   
   > On 1/30/2026 3:01 PM, Paul B. Andersen wrote:   
   >   
   >>  v(t) is a function of t defined by:   
   >>  v(t) = kt where k is a constant   
      
   >> The point is that dv/dt = k for all t.   
   >>   
   >> That includes at t = 0 when v = 0.   
   >>   
   >> If v is a speed and t a time,   
   >> then k is a constant acceleration.   
   >>   
   >> So dv/dt may be different from zero even if  v = 0.   
      
   > And is it, poor trash? Is your "v" some speed?   
   > What speed?   
      
   Yes, dv/dt may be different from zero even if v = 0.   
      
   And this fact will not go away because your shark is eating gras.   
      
   How do you think Newton would have answered the following   
   questions?   
   An object with mass m is stationary when t < 0.   
   At the time t = 0 a force F is applied on the body.   
   Q1: What is the body's speed at t = 0?   
   Q2: What is the body's acceleration dv/dt at the time t = 0?   
      
   Would he have said that the body can never accelerate because   
   it's speed is zero?   
      
   >> If a spaceship with mass m = 1000 kg is pushed by a rocket engine   
   >> with the force F = 10000 N, then its proper acceleration is   
   >> a = F/m = 10 m/s².   
      
   > Sure, and a proper sharks eat grass.   
      
   >> You are in the spaceship, maybe on your way to Mars. But you are   
   >> far from Earth and Mars, and Mars is not in front of you yet.   
   >> Your acceleration is obviously the same as the spaceship's,   
   >> but you don't know what it is.   
   >> How will you measure your acceleration?   
   > I'll use The Force. In a fantasy gedankenwelt   
   > I can do it, can't I, poor trash?   
      
   >> By dv/dt? Which v? Your speed relative to a planet? Which planet?   
   >> The only reference you have is your spaceship which is accelerating.   
   >>   
   >> A physicist may define your proper acceleration something like this:   
     > And he can define a proper shark as a a farm animal with   
   > thick wool that eats grass and is kept for its wool,   
   > skin, and meat. He's an idiot, why wouldn't he?   
      
   >> Your proper acceleration is the acceleration measured in the   
   >> momentarily co-moving inertial frame of reference.   
   >> That would probably not help you, so there is only one way to do it.   
   >> You would use an accelerometer. It will show the acceleration 10 m/s².   
   >>   
   >> An accelerometer measures the acceleration in its own rest frame,   
   >> where its speed is zero. But dv/dt = 10 m/s² even if v = 0.   
      
   > And a shark eats grass. You're a complete   
   > idiot buying this crap. Velocity "in own   
   > rest frame" is always 0, no acceleration.   
   > Sorry, trash.   
   You sit in your car with an accelerometer in your hand.   
   The accelerometer shows that your acceleration is a = 2 m/s².   
   According to the accelerometer dv/dt = 2 m/s².   
   What is v?   
      
   --   
   Paul   
      
   https://paulba.no/   
      
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