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How Things Work

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					What is science / physics?
•A consistent picture of how the
 world works
•Backed up by data
•Predictive
•Done by (relatively) normal
 people
•Evolving
•Useful for technology
•Sometimes transformational for
 humanity
Big ideas
 •Newton’s 3rd law
 •Work and conservation of
  energy, mechanical advantage
 •Friction and Entropy, 2nd law
  of thermodynamics
 •Mass and Weight
 •Heat
 •Phases of matter
 •Radiation and light
 •CMBR
 •Electromagnetic induction
 •Structure of atoms and nuclei
 •Resonance
How things work
•Bicycles
•Air conditioners / refrigerators / dehumidifiers
•Car engines
•Light bulbs
•Atomic clocks, GPS
•Circuits, flashlights
•AC power distribution
•Generators, Motors
•Radio, cell phones
•Microwave ovens
•Nuclear weapons and power
•X-rays, CAT scans, MRI, radiation therapy
Many of you went outside
of your comfort zone…

          …good for you!
A battleship simultaneously fires two shells
toward two enemy ships, one close by (A), one
far away (B). The shells leave the battleship at
different angles and travel along the trajectories
indicated below. Which of the two enemy ships
gets hit first?




                (Muzzle speed is constant)
Two light bulbs are connected in series to a
battery. When a wire is connected across light
bulb 1, light bulb 2

                 2        1




(A) glows more brightly   (B) glows more dimly
(C) does not change       (D) goes out
Two uniformly charged spheres are fastened to
pucks on an air hockey table. The charge on
sphere 2 is three times the charge on sphere 1.
Which force diagram correctly shows the
magnitude and direction of the electric forces:


    (A)                    (C)



    (B)                    (D)
A box, with its center-of-mass off-center as
indicated by the dot, is placed on an inclined
plane. In which of the four orientations shown,
if any, does the box tip over?
A ladybug sits at the outer edge of a merry-go-round,
and a gentleman bug sits halfway between her and the
axis of rotation. The merry-go-round makes a complete
revolution once each second. The gentleman bug’s
angular speed is




 A. half the ladybug’s.    B. the same as the ladybug’s.
 C. twice the ladybug’s.   D. impossible to determine
A 10-kg weight is suspended from the ceiling by a
spring. The weight-spring system is at equilibrium
with the bottom of the weight is about 1 m above
the floor. The spring is then stretched until the
weight is just above the eggs. When the spring is
released, the weight is pulled up by the
contracting spring and then falls back down under
the influence of gravity. On the way down, it


 (A) smashes the eggs
 (B) reverses its direction far above the eggs
 (C) reverses direction exactly when it reaches the eggs
   A nitrogen nucleus has 15 nucleons. The atomic
   number of nitrogen is 7. The number of protons in
   this nucleus is

(A) 7
(B) 8
(C) 15
(D) 22
   A tank circuit is built from which components?



(A) Battery and inductor
(B) Inductor and capacitor
(C) Capacitor and resistor
(D) Resistor and battery
  An MRI device uses



(A) Magnets and gamma rays
(B) Magnets and beta rays
(C) Magnets and alpha rays
(D) Magnets and radio waves
  A CT scan uses



(A) X rays
(B) Microwaves
(C) Delta rays
(D) Lasers
   When an air conditioner cools a room, it



(A) decreases the air pressure in the room.
(B) decreases the entropy in the room.
(C) decreases the entropy outside of the room.
(D) violates the second law of thermodynamics.
   The musical scale where each successive note has
   a frequency bigger by a factor of the twelfth root
   of 2 (approximately 1.06) is called the

(A) well-done scale.
(B) well-tempered scale.
(C) equal-tempered scale.
(D) hot-tempered scale.
I hope that you had fun in PHYS 140!


     Keep in touch!

				
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posted:8/10/2012
language:English
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