A student hangs a pith ball from a stand using thread and rubs a glass rod with silk cloth. Upon bringing the glass rod near the pith ball, the student observes that the pith ball is attracted towards the glass rod, as shown. How can the observation best be explained?
A. The glass rod exerts a gravitational force , causing it to attract the pith ball.
B. The pith ball exerts a replusion force towards the glass rod, causing the attraction
C. An electric field exists between the glass rod and the pith ball, causing the attraction
D. Electric charges in the string transfer to the pith ball, causing it to attract the glass rod.

moving ball hits still ball. mover stops, hit ball moves. momentum transfer.

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.