Chapter 3: Q34P (page 125)
The left side of Figure 3.62 shows a proton and an electron. (a) What is the direction of the electric force on the electron by the proton? (b) What is the direction of the electric force on the proton by the electron? (c) How do the magnitudes of these forces compare? The right side of the figure shows two electrons. (d) What is the direction of electric forces on electron A due to electron B? (d) What is the direction of electric forces on electron B due to electron A? (d) How do the magnitudes of these forces compare.

Short Answer
- The electron will move upwards.
- The proton will move downwards.
- The magnitude of the forces will be same, since charges and distance is same for the part (a) and (b).
- The electron A will move away or upwards.
- The electron B will move below or downwards
- The magnitude of the forces will be same, since charges and distance is same for the part (e) and (f).

, the mass of the Earth is
, and the center-to-center distance is
. How far from the center of the Sun is the center of the mass of the Sun-Earth system? Note that the Sun’s radius is
.
moving with velocity
. At the same instant object 2 is at location
, moving with velocity
. a) what is the location of the center of mass of the two equal mass objects? b) What is the velocity of the center of mass?