Recent content by D'Alembert

The field in the centre of the Earth is zero as well as the potential. Think of Newton's apple.

I guess it is because r is the symbol used for the position vector.

Angular acceleration is ω^{2}r. You can represent it also as a cross product: ω\times(ω\timesr) Now use the Right Hand Rule and you will come to the direction known for the angular acceleration.

As for converting linear to angular momentum you have to know that everything that has linear momentum has angular momentum too and the other way round. When it comes to the collision the energy of the ball is given to the door as momentum. The only motion that the door can perform is a...

This is not perfectly valid, because it depends on the permitivity of the cylinder. According to Faraday a metall would shield away every electric field. But if you plot the field, you will see, that the field gets into the hollow space.

Why do you plug the vector in it when you have just one component z. It is not V(r) but V(z), so that the vector is not needed.

Mathematicians alway try to present mathematics as independent from experience and the nature. Einstein once raised the same question like you how mathematics can explain nature so well when it has nothing to do with it. The clear reason for it is, that all axioms of mathematics are basing on...

The answer is much simplier than you can think. The Lenz-Vector is defined as follows: A=p\timesL - m\alphae_{r} m\alphae_{r} is a constant. Therefore \frac{d}{dt} m\alphae_{r}=0 As p\timesL is a constant too, \frac{d}{dt}A=p\timesL - m\alphae_{r}=0 shows that the...