In the Fourier heat equation we have dT/dt = alpha * (d^2T/dx^2), with alpha being the proportionality constant. What I do understand is the relation between derivatives of x and t, but why the proportionality constant? How does it even make sense?

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

f=ma a/f/m a= 480/60 a = 8m/s/s that is quick wow

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.