Velocity is also a vector with speed & direction. Changing either over time is an acceleration. Moving the velocity in a circle at constant speed creates an acceleration vector that points toward the center of the circle. Or the “instant center” of a varying curve like an elipse. That’s what gravity does.

You wouldn’t create an imaginary force holding your head back when the car accelerates forward, would you? You know it’s inertia, a property of mass. Lateral acceleration creates the same feeling, only “sideways. It’s still inertia. The problem is that you’re inside the car, itself a non-inertial reference frame.

Norm

Nachdem ich ja bereits auf Möglichkeiten gestossen bin, ein Lichtschwert zu kaufen, zweifle ich nun erneut (ein wenig), ob es die “Star Wars”-Galaxie nicht vielleicht doch gibt. Das folgende Bild wurde von der NASA-Raumsonde Cassini in der Nähe des…

“Hell yeah I’m disappointed. A giant orbital battle station hiding in our solar system, how cool would that be? How much gravity would the death star exert though? I’ve checked it out and it’s diameter is 900km, making it bigger than Mimas, although it would have a lot less mass.”

Well, what I was getting at, Tom, was that if the Death Star were in our solar system, its next target was unlikely to be Rhea or Io (for instance), but most likely to be the only inhabited body in our system. I think the gravity it exerts would be the least of our worries. Or maybe it got overtaken by a Vogon Constructor Fleet, I dunno …