A car travels 60 km in the first 2 hours and 68 km in the next 2 hours. what is the cars average speed ?

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.

this means that the temperature of both substances will be equal