The zirconium nucleus contains 40 protons, and an electron is 1.0 ...

[washai]

The zirconium nucleus contains 40 protons, and an electron is 1.0 nm from the nucleus. What is the electric force on the electron due to the nucleus? ( e = 1.60  10-19 C, k = 1/40 = 9.0  109 N  m2/C2 )
 
  A) 2.9 nN
  B) 1000 C
  C) 3.7 nN
  D) 6.8 nN
  E) 9.2 nN

Question 2

A 1.0-g bead is at (-2.0 cm, 2.0 cm), a 2.0-g bead is at (2.0 cm, -4.0 cm), and a 3.0-g bead is at (2.0 cm, 0.0 cm). What are the coordinates of the center of mass (or center of gravity) of this system of beads?
 
  What will be an ideal response?

[ryansturges]

Answer to Question 1

E

Answer to Question 2

1.3 cm, -1.0 cm