Exam2 Review - 1
Phys1110 Exam 2 Review:
Everything from Exam I!

algebra, trigonometry, unit conversions,

1D Motion:

x
v
, a 
, graphs, slopes
t
t
constant acceleration formulas: v
vo
a t , etc
Vectors! vector addition, vector components
v 
2D Motion:
v
 a
,
t

y
v1  v  v 2
a
Projectile Motion
vy
treat x- and y-motions independently
ax = 0  vx = constant
ay = – g  vy = voy – g t , etc
ax = 0
ay = –g
vo

x
vx

Circular Motion with constant speed v,
v2
a  a 
r
a and Fnet are toward the center (centripetal)
v
a
a
 Newton's Laws
Fnet  F1  F2  F3  .. 
r
v
F
i
i
NI: Fnet  0

v  constant
NII: Fnet  m a
NIII: FAB   FBA
FAB
A
FBA
B
New material since Exam I
Force and motion problems with one or more bodies:
1) Draw Free-body diagram
2) Choose Coordinate system
3)  Fx  m a x ,  Fy  m a y
10/25/2017
 University of Colorado at Boulder
Exam2 Review - 2
Friction f
 sliding friction: f = K N
 static friction:
0 < f < fmax = S N
Work and Energy

work done by force F: WF  F  r , work can be (+), (), or zero

Hooke's Law: Fspring =  k x

work-energy principle: Wnet  KE

Definition of PE associated with conservative force F: PEF   WF

PEgrav = m g h

If no sliding friction, so no thermal energy generated : Emech = KE + PE = constant

If sliding friction, KE + PE + Ethermal = constant

Power P 
(k = spring constant)
PEelastic = (1/2) k x2
W
t
Gravity
Newton's Universal Law of gravity:
m1 m 2
F  G
r2
m1 F
F
m2
r
distance measured from centers
Acceleration due to gravity
Fnet  m a
GMm
r2
 mg

g 
Planet
mass M
GM
r2
R
mass m,
in free-fall
r = distance to center of planet
r
Orbits, Kepler's laws
GMm
r
Know how to use conservation of energy to derive escape speed.
PEgrav  U(r)  
10/25/2017
 University of Colorado at Boulder
Exam2 Review - 3
To prepare for Exam 2:
 Review Concept Tests, MP problems, Tutorial HW, FlipIt questions. (Read question and
try to remember reasoning that gets to the answer)
 When reviewing MP problems, know how to derive algebraic formula for answer.
 Prepare your formula sheet.
 Take the practice exam.
 It is no good to memorize answers. You have to understand and remember how you
construct the answers.
Problem solving strategies.
There are more than a 1000 equations in this course, but there are only a handful of problemsolving strategies. The most important step in solving a problem is always the FIRST STEP,
which is to decide: what is the correct strategy for attacking the problem?
Fortunately, there are only about 4 strategies in this course:
 Problems involving forces and motion: Use Fnet = ma.Start by drawing a free-body
diagram, then choose a coord. system, then write the equations.
Some special cases of Fnet = ma problems are : Static equilibrium problems (Fnet = 0) and
constant acceleration problems.
 Before/after situations: Apply a conservation law.
o Conservation of energy (always true, but most useful when there is no friction)
 Vector math. Example: vector1 – vector2- delta vector problems.
 Apply the definition: For instance if you are asked to compute the work done by a force, you
have to know the definition of work.
10/25/2017
 University of Colorado at Boulder