Newtonian Mechanics REVIEW F F21 = (m1+m2+m3)a F21 = m1a

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Newtonian Mechanics

• Review

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Center of Mass
http//learning.physics.iastate.edu/DemoRoom/Image
s/BalancingBird.png
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Kinematics
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Kinematics
Keep track of positive and negative directions!
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Free Fall
5m
20m
45m
80m
125m
http//www.physicsclassroom.com/Class/1DKin/U1L5b3
.gif
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Projectile Motion
Keep x and y separate. Acceleration is only in
y-direction.
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Dynamics
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Newtons 1st
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AAAAAAAAACw/YQx_nzZUWvE/s1600/Photo1.jpg
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Newtons 2nd
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00803211542354796922.GIF
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Newtons 3rd
http//serc.carleton.edu/images/introgeo/interacti
ve/examples/_1185845655.jpg
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Free Body Diagrams
Do not resolve!
http//www.physicsclassroom.com/class/newtlaws/u2l
2c6.gif
http//buphy.bu.edu/duffy/PY105/7d.GIF
http//ffden- 2.phys.uaf.edu/211_fall2004.web.dir/
Jeff_Levison/freebody_diagram.jpg
http//i21.tinypic.com/ojmhc1.jpg
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Free-Body Diagrams

• Possible forces
• Gravity
• Normal
• Tension
• Friction
• Applied
• Electrostatic
• Electromagnetic
• Do Not Draw
• Centripetal Force
• Air Pressure

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Atwood Machine

• Look at each mass independently
• Choose your /- directions
• Label ALL the forces acting on that object
• Solve for common pieces and substitute or set
  equal to one another

http//upload.wikimedia.org/wikipedia/commons/thum
b/6/6e/Atwood_machine.svg/240px-Atwood_machine.svg
.png
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Remember
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Friction
http//carfullofpandas.com/comics/2007-11-18-frict
ion.jpg
http//www.school-for-champions.com/science/images
/friction_uses-bear.jpg
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Work, Energy, Power
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Work
http//www.wohill.com/images/Push_box_pictogram.jp
g
http//www.selfstoragetameside.co.uk/images/storag
e/carry_box_lrg.jpg
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Work-Energy Theorem
http//thefreegeorge.com/thefreegeorge/wp-content/
uploads/2011/02/d02_17981149.jpg
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Work?
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Power
http//www.physicslessons.com/power-equation.gif
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Energy

• Kinetic
• Potential (Grav Spring)
• Rotational Kinetic
• Electrical
• Chemical
• Nuclear

http//www.alistaircraven.com/java/basic/energy4.j
pg
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KE and GPE
Whats wrong with this picture?
http//www.world-of-waterfalls.com/images/mgh2mvsq
_coasterL.gif
http//www.enwin.com/kids/images/pic.roller_coaste
r.jpg
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Momentum

• Pmv

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Impulse-Momentum Theorem
http//river.vansd.org/14544/physicsweb/hon_physic
s/studyguide/Image112.gif
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Conservation of Momentum

• Always Conserved initially!

http//onlinephys.com/collisionwagons.gif
http//www.tpub.com/content/doe/hdbk1010/img/hdbk1
010_90_2.jpg
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Elastic vs. Inelastic

• Kinetic Energy is conserved
• Kinetic Energy is not conserved

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Circular Motion
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http//www.batesville.k12.in.us/physics/phynet/mec
hanics/circular20motion/labs/images/ucm_app.gif
http//allphysicsequations.com/image_sci_forces001
.jpg
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Rotational KinematicsRotational Dynamics
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Torque
http//www.physics247.com/physics-homework-help/be
am.jpg
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Gravitation
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Oscillations and SHM
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Period vs. Frequency
http//www.calctool.org/CALC/other/converters/freq
.png
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Practice Questions
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Practice Problem 1

• A shotputter throws the shot with an initial
  speed of 15.5 m/s at a 34.0 angle to the
  horizontal. Calculate the horizontal distance
  traveled by the shot if it leaves the athletes
  hand at a height of 2.20 m above the ground.

25.6 m
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Practice Problem 2a

• Three blocks on a frictionless horizontal surface
  are in contact with each other, as shown below.
  A force F is applied to block 1 (mass m1).
  Determine the acceleration of the system (in
  terms of m1, m2, and m3).

http//webassign.net/walker/05-19alt.gif
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Practice Problem 2b

• Three blocks on a frictionless horizontal surface
  are in contact with each other, as shown below.
  A force F is applied to block 1 (mass m1). If m1
  m2 m3 12.0 kg and F 96.0 N, then
  determine the net force on each block.

F1 F2 F3 32 N
http//webassign.net/walker/05-19alt.gif
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Practice Problem 2c

• Three blocks on a frictionless horizontal surface
  are in contact with each other, as shown below.
  A force F is applied to block 1 (mass m1). If m1
  m2 m3 12.0 kg and F 96.0 N, then
  determine the force of contact that each block
  exerts on its neighbor.

F12 F21 64 N
F23 F32 32 N
http//webassign.net/walker/05-19alt.gif
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Practice Problem 3

• A window washer pulls herself upward using a
  bucket-pulley apparatus. How hard must she pull
  downward to raise herself slowly at a constant
  speed? The mass of the person plus the bucket is
  65 kg.

318.5 N
http//www.solutioninn.com/images/P-M-L-M20(338).
PNG
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Practice Problem 4

• A window washer pulls herself upward using a
  bucket-pulley apparatus. How hard must she pull
  downward to raise herself slowly at a constant
  speed? The mass of the person plus the bucket is
  65 kg.
• If she increases this force by 15, what will her
  acceleration be?

1.47 m/s2
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Practice Problem 5a

• A 28.0-kg block is connected to an empty 1.35-kg
  bucket by a cord running over a frictionless
  pulley as shown in the picture. The coefficient
  of static friction between the table and the
  block is 0.450 and the coefficient of kinetic
  friction between the table and the block is .320.
  Sand is gradually added to the bucket until the
  system just begins to move.
• Calculate the mass of sand added to the bucket.

12.6 kg
http//img160.imageshack.us/i/untitled4bd.jpg/sr1
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Practice Problem 5b

• A 28.0-kg block is connected to an empty 1.35-kg
  bucket by a cord running over a frictionless
  pulley as shown in the picture. The coefficient
  of static friction between the table and the
  block is 0.450 and the coefficient of kinetic
  friction between the table and the block is .320.
  Sand is gradually added to the bucket until the
  system just begins to move.
• Calculate the acceleration of the system.

0.88 m/s2
http//img160.imageshack.us/i/untitled4bd.jpg/sr1
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Practice Problem 6

• A 0.15 kg ball moving at 40 m/s is struck by a
  bat.   The bat reverses the ball's direction and
  gives it a speed of 50 m/s.  What average force
  does the bat apply to the ball if they are in
  contact for 6.0 x 10-3 s?

2.3 x 103 N
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Practice Problem 7

• A flat puck (mass M) is rotated in a circle of
  radius R on a frictionless air-hockey tabletop,
  and is held in this orbit by a light cord
  connected to a dangling block (mass m) through a
  central hole as shown below. Derive an
  expression for the speed of the puck.

http//www.ux1.eiu.edu/cfadd/1350/Hmwk/Ch06/Image
s/FigP6.51.gif
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Practice Problem 8a

• A ball attached to a string swings in a circle of
  radius 1.20 m at 28o angle with the vertical. 
  The tension in the string is 1.80 N. What is the
  mass of the ball?

0.16 kg
http//library.thinkquest.org/25844/circular_motio
n/images/question.gif
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Practice Problem 8b

• A ball attached to a string swings in a circle of
  radius 1.20 m at 28o angle with the vertical. 
  The tension in the string is 1.80 N. How long
  does it take the ball to complete one orbit?

4.2 sec
http//library.thinkquest.org/25844/circular_motio
n/images/question.gif
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Practice Problem 9

• A uniform 1500-kg beam, 20.0 m long, supports a
  15,000-kg printing press 5.0 m from the right
  support column. Calculate the force on each of
  the vertical support columns.

44,100 N in the far beam (left) 118,000 N in the
close beam (right)