Answer:
1.if you rub two pieces of the same material together neither piece becomes charged because they hold onto their electrons with the same strength. If you rub a piece of styrofoam in your hair, the styrofoam picks up electrons from your hair and becomes negatively charged.
2.The effect is,boxes must be fall or the boxes may change its position.
3.The definition of an observation is the act of noticing something or a judgment or inference from something seen or experienced. An example of observation is the watching of Haley's Comet. An example of observation is making the statement that a teacher is proficient from watching him teach several times.
