You can chew through very tough objects with your incisors because they exert a large force on the small area of a pointed tooth. What pressure in Pa can you create by exerting a force of 490 N with your tooth on an area of 0.900 mm2

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.

if you answer my question i will answer yours

grav forces affect all objects magnetic forces affect magnetic objects and electric currents