the Doppler effect. (I don't know how to explain it lol)
Answer :
Velocity will be 
Explanation:
We have given glass surface has a diameter of 1.5 mm
And charge q = 1.60 nC
Radius of electrons orbit r = height of electron above surface + radius of sphere = 
Force on electron is given by
, here q is charge on sphere and e is charge on electron

This force work as centripetal force
So 

v = 
The answer would be number four. I'm sorry if I am too late. Byes.....
Answer:
Explanation:
the force that you applied caused the notebook to move.
the force applied on the notebook by the table causes it to stop moving.
this is because after sometime the book uses up the force and later the force you applied is less than that of the force by the table.