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visits member for 2 years, 10 months
seen 2 days ago

Sep
15
revised Blowing your own sail?
reverser is a noun, not thruster
Sep
15
revised Why are some forces not included in the sum of forces?
use mathjax where appropriate
Sep
15
suggested suggested edit on Blowing your own sail?
Sep
15
suggested suggested edit on Why are some forces not included in the sum of forces?
Sep
15
revised Why is Buoyant Force $V\rho g$?
it's second law of motion and the equilibrium assumption, not the third law
Sep
15
answered Why is Buoyant Force $V\rho g$?
Sep
12
comment Is there a classical analog to quantum mechanical tunneling?
@garyp: Photons are just as much particles as any other elementary particles. They all have both particle and wave properties, just different fields are involved.
Sep
5
revised If everything is relative to each other in this universe, why do we keep the Sun to be the reference point?
fixed some typos
Sep
5
suggested suggested edit on If everything is relative to each other in this universe, why do we keep the Sun to be the reference point?
Sep
2
comment Water bottle moment of inertia
Moment of inertia depends not only on mass, but on its distribution. And that is not constant for bottle with some liquid.
Sep
1
comment How does escape velocity relate to energy and speed?
@Jim: For bodies that are not rotationally symmetrical the expression remains complicated even above the surface. Even the definition of "centre" is not obvious there.
Sep
1
comment How does escape velocity relate to energy and speed?
@Jim: Well, under the surface one would have to substitute proper formula for gravity inside a body. Trying to talk about what happens without that is somewhat misleading, yes.
Sep
1
comment How does escape velocity relate to energy and speed?
@Jim: If you are below the surface, the material above you cancels some of the gravity and the forces perfectly balance in the centre, so effectively $M$ goes to $0$.
Aug
30
comment Why is it easier to walk diagonally upstairs
Whether power is lower depends on speed. It needs to be explained why the speed will not increase on the shallower slope to make up for the reduced force.
Aug
27
accepted Conservation of energy in a different frame of reference
Aug
27
comment Conservation of energy in a different frame of reference
@dmckee: I understand why work. I would welcome some hint at how to qualify it and verification it comes out $-mv_0\Delta v$.
Aug
26
asked Conservation of energy in a different frame of reference
Aug
20
comment Are voltages discrete when we zoom in enough?
Since $e$ is a charge and $k$ is dimensionless (natural number), $k\cdot e$ is still a charge, not an electric potential (voltage).
Aug
5
comment What does centre of lift depend on?
@MikeDunlavey: Make that an answer please; the bit about the curvature of the flow is what I was missing.
Aug
5
revised What does centre of lift depend on?
added 120 characters in body