A4 kg block slides down a rough inclined plane inclined at 30° 179009.gif with the horizontal. determine the coefficient of kinetic friction between the block and the surface if the block has an acceleration of 1.2 m/s2.

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.