8
Friction
5.1
Friction
Static friction no relative motion (stiction)
Kinetic friction with relative motion
FN
F = FN
FA
FF
FF
0<1
coefficient of friction
mg
FA
Friction
Static friction no relative motion (stiction)
Kinetic friction with relative motion
F
4
Vectors
Coordinate systems and vectors
A coordinate system is a set of two (or more) numbers
used to determine the position of an object in a space with
respect to other objects in that space.
Examples of coordinate systems:
Cartesian (x, y,
y) z)
z)
9
Circular Motion
1 - Uniform Circular Motion
5.2
v1
v2
r1
r2
+
v
-v1
v = v2 v1
v2
j
j
v
y
vy = v cos
i
vx = -v sin
y = r sin
r
x = r cos
x
i
j
j
v
v vsin
vxi viy j vcosj
sin y/r
y = r sin
y
vy = v cos
i
vx = -v sin
r
cos x/r
v (vy/r)i (vx/r) j
d
d
3
One Dimensional Kinematics
6 Solving Problems
Example Problems
1. An object with an acceleration a = +3.2 m/s2 at a certain instant has a
velocity v = 9.6 m/s. What is v at a time 2.5 s earlier and 2.5 s later?
x
v
a
t
v vo at
v(t 2.5) vo a(2.5s)
v(t 2.
3
One Dimensional Kinematics
2 Average Velocity
average velocity = vavg =
Graphically:
vavg= slope of straight line connecting end points x2 and x1
x
x2
slope = vavg
x1
t
t1
t2
average speed = savg =
total distance covered
t
Example: Circular drive of rad
3
One Dimensional Kinematics
7 Freefall
Free-fall acceleration
at Earths surface
a 9.8 m 2
s
define the gravitational acceleration
thus at Earths
surface
a g
g 9.8 m 2
s
At t = 0, a child drops a ball from a building. Where is the ball 1.5 s later?
yo
79. PY205/TEST1/F02 001
If it were possible to walk, without stopping, once around the earth's equator at a constant speed of 2 m Is,
how many days would it take? The circumference of a circle is 2m. The earth's mean radius is 6.37 x 106 m.
To two signifi
PY205N
Name (print)_
Spring 2014
Test 1 Version A
ID# _
Time limit: 90 minutes for entire test
Closed book
Section#_
HONOR CODE
I have neither given nor received unauthorized aid on this test. Signed:_
General information and instructions: On the blank Sc
95. PY205 /TE5Tl /503 001
A light-year is the distance traveled by a light wave in one year. Given that light travels at 3 x 108
how many meters does it take to make one light-year? In order of magnitude,
(A) 1016
(B) 1010
(C) 1012
(D) 1014
ml s,
(E) 1018
PY205N
Name (print)_
Spring 2012
TEST 1, practice version
ID# _
Time limit: 75 minutes for entire test
Closed book
Section#_
HONOR CODE
I have neither given nor received unauthorized aid on this test. Signed:_
General information and instructions: On the
PY205N
Name (print)_
Fall 2013
TEST 1, Version A
ID# _
Time limit: 75 minutes for entire test
Closed book
Section#_
HONOR CODE
I have neither given nor received unauthorized aid on this test. Signed:_
General information and instructions: On the blank Sca
PY205N
Name (print)_
Spring 2012
TEST 1, version A
ID# _
Time limit: 75 minutes for entire test
Closed book
Section#_
HONOR CODE
I have neither given nor received unauthorized aid on this test. Signed:_
General information and instructions: On the blank S
PY205N
Spring 2015
Practice Exam
Time limit: 90 minutes for entire test
Closed book
At the test you will be given the following instructions: On the blank Scantron sheet, (1) print
and bubble in your name where indicated in the upper right corner; then (2
PY 205 Problem Session 3
Group members (no more than 3):_
You have taken a summer job at a warehouse and have designed a method to help get heavy
packages up a 15 ramp. In your system a package is attached to a rope which runs parallel to the
ramp and ove
PY 205 Problem Session 1
Group members (no more than 3):_
The Starship Enterprise returns from warp drive to ordinary space with a forward speed of 50 km/s.
To the crews great surprise, a Klingon ship is 100 km directly ahead, travelling in the same direc