3 ms·

The falling object doesn't accelerate. You, standing on the ground are the one that's accelerating. You see the object as accelerating but that's an illusion du

The falling object doesn't accelerate. You, standing on the ground are the one that's accelerating. You see the object as accelerating but that's an illusion due to frames of reference. As evidence: which object feels a force on it? You can feel the force the ground continually pushes up at you. The ground is accelerating you up. The falling object is completely idle in its inertial frame and feels nothing.

colordrops 6y ago
Ok so that makes sense, but if we are accelerating by standing on the ground, isn't that implying that we are continuously increasing in energy? Couldn't that be harvested for a perpetual motion machine of some sort?
- drdeca 6y ago
  First, "it all adds up to normality". Second, hm, I'm not sure. Well, the glass on the table next to me is "accelerating", but in my frame of reference (which is the same as that of the glass) it is also stationary...? If I drop a ball above the glass, and we consider things from the frame of reference where the ball is stationary, which (neglecting air resistance) is an inertial reference frame. In this frame, the glass is accelerating ball-wards , because of the table pushing on it, and, this force is applied over a distance as the glass approaches the ball. So, yes, it seems that the KE of the glass should be increasing in the reference frame of the ball. Hm, I'm confused. I suppose if we consider a geodesic representing a periodic orbit around the earth, that the positions and velocities of various objects on earth will be in a cyclic pattern?
  - colordrops 6y ago
    The layman descriptions are probably incomplete or rough abstractions missing nuance. Reminds me of the idea of a rubber membrane with balls on it representing the curvature of spacetime explaining how gravity works - I've always disliked that example because you still need plain old gravity to pull the balls into the membrane.
- gilgoomesh 6y ago
  Energy is Force times Distance. You're not moving (even though you're accelerating) so there's no energy expended. See Veritasium's video at 10m17s: https://youtu.be/XRr1kaXKBsU?t=617 https://youtu.be/XRr1kaXKBsU?t=617 He addresses that basic science makes this confusing because there's a curvature term that is usually left out of acceleration equations which balances out when you're accelerating along your curvature (e.g. against gravity), instead of along your spatial coordinates.
  - colordrops 6y ago
    Nice, that's it, thank you

colordrops 6y ago

Ok so that makes sense, but if we are accelerating by standing on the ground, isn't that implying that we are continuously increasing in energy? Couldn't that be harvested for a perpetual motion machine of some sort?

drdeca 6y ago
First, "it all adds up to normality". Second, hm, I'm not sure. Well, the glass on the table next to me is "accelerating", but in my frame of reference (which is the same as that of the glass) it is also stationary...? If I drop a ball above the glass, and we consider things from the frame of reference where the ball is stationary, which (neglecting air resistance) is an inertial reference frame. In this frame, the glass is accelerating ball-wards , because of the table pushing on it, and, this force is applied over a distance as the glass approaches the ball. So, yes, it seems that the KE of the glass should be increasing in the reference frame of the ball. Hm, I'm confused. I suppose if we consider a geodesic representing a periodic orbit around the earth, that the positions and velocities of various objects on earth will be in a cyclic pattern?
- colordrops 6y ago
  The layman descriptions are probably incomplete or rough abstractions missing nuance. Reminds me of the idea of a rubber membrane with balls on it representing the curvature of spacetime explaining how gravity works - I've always disliked that example because you still need plain old gravity to pull the balls into the membrane.
gilgoomesh 6y ago
Energy is Force times Distance. You're not moving (even though you're accelerating) so there's no energy expended. See Veritasium's video at 10m17s: https://youtu.be/XRr1kaXKBsU?t=617 https://youtu.be/XRr1kaXKBsU?t=617 He addresses that basic science makes this confusing because there's a curvature term that is usually left out of acceleration equations which balances out when you're accelerating along your curvature (e.g. against gravity), instead of along your spatial coordinates.
- colordrops 6y ago
  Nice, that's it, thank you