Phy 2049: Physics II
Syllabus, grades and exams
2.
Electricity, Magnetism, optics
3.
Electricity
q1q2
F k
Charge
2
r12
Force
k  9  109
Constants
1
1.

4o
2049, summerC, ‘07
Phy 2049: Physics II
F k
q1q2
r12
2
k  9  10
1

4o
9
rˆ
• Coulomb’s Law
• F in Newtons, r in meter, q in
Coulomb and k is the fix.
• F is a vector, directed along a line
joining the charges.
• The force can be added like a
vector
Phy 2049: Physics II
Two equally charged particles are held 2.5X
10-3 m apart and then released from rest.
The initial acceleration of the first particle is
observed to be 5.0 m/s2 and that of the
second to be 11.0 m/s2. The mass of the
first particle is 6.3X10-7 kg.
What is the mass of the second particle?
[2.86e-07] kg
What is the magnitude of the charge of each
particle? [4.68e-11] C

Phy 2049: Physics II
Two equally charged
particles are held 2.5X 10-3
m apart and then released
from rest. The initial
acceleration of the first
particle is observed to be 5.0
m/s2 and that of the second to
be 11.0 m/s2. The mass of the
first particle is 6.3X10-7 kg.
What is the mass of the second
particle?

What is the magnitude of the
charge of each particle?




M1a1= M2a2 = F = kq2/r2
M2= M1a1/a2 = 2.86x10-7 kg
q2 = r2 M1a1/k
q = 4.68x10-11 C
Phy 2049: Physics II


In Fig. 21-22, the
particles have charges
q1 = -q2 = 298 nC and
q3 = -q4 = 280 nC, and
distance a = 4.0 cm.
What are the a) x
[0.607] N and b) y [0.303] N components of
the net electrostatic
force on particle 3?
Phy 2049: Homework

Because the summer semester is quite
short, the homework assignments are
rather large. I would suggest that you
do as many as you can at the earliest
chance possible. I would certainly urge
you not to try them all the night before
they are due.
Phy 2049: Homework




Visit Webassign (http://www.webassign.net)
Physics is a little like riding bicycle. No
one has learned how to ride a bicycle
by reading an owner’s manual.
It is very hard in the beginning, but
then it becomes instinctive. That is
when you start to enjoy the scenery
Try doing homework in a group.
Phy 2049: Homework


Coulomb’s law
Addition of forces as vectors