MCAT PHYSICS REVIEW

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MCATPHYSICS REVIEW
January 30, 2006 Dr. Ponn Maheswaranathan
(Mahes)Office Sims 213-B, Phone 323
4940E-mail MAHESP_at_WINTHROP.EDUOffice Hours M
and W 10-1150.
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Online Resources

• http//www.aamc.org/mcat
• Cutnell and Johnson
• Giancoli
• http//www.scientia.org/cadonline/home.html
• http//www.geocities.com/CollegePark/Union/5092/
• http//www.udayton.edu/premed/UCMCATReview/MainPa
  ge.htm

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Major Physics Topics

• Translational Motion
• Force and Motion, Gravitation
• Equilibrium and Momentum
• Work and Energy
• Wave Characteristics and Periodic Motion
• Sound
• Fluids and Solids
• Electrostatics and Electromagnetism
• Electric Circuits
• Light and Geometric Optics
• Atomic and Nuclear Structure

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Translational Motion

• Units and dimensions
• Vectors Components and addition
• Speed, velocity, and acceleration
• Freely falling bodies

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Units and dimensions
Systems of units
CGS-- Centimeter, gram, and secondSI----- The
international systemBE/USC-- British Engineering
or the US customary
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SI Base Quantities and Units
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Significant Figures
A radar signal is sent from Earth to a planet
which is 7 x 1010 m from Earth. How long will it
take for the signal to return to Earth? A. 200
s B. 300 s C. 400 s D. 500 s
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Vectors and Scalars
Physical quantities are divided into vectors and
scalars. Scalars have magnitude or size only.
Vectors have magnitude and direction.
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Components of a Vector
Use Cosine for Adjacent component and Sine for
opposite component.
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Vector Addition
Example problem Locating a lost plane
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Speed and Velocity

• Average speed, v, is obtained by dividing travel
  distance, d, by travel time, t.

The speed at a particular time is known as the
instantaneous speed. When you drive, the
speedometer of a car displays the instantaneous
speed. Speeding tickets are issued using the
instantaneous speed. Velocity Speed with
direction.
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Acceleration
Acceleration, a, is the time-rate at which the
velocity changes. It is obtained by dividing the
change in velocity by the time it took for that
change.
Acceleration is a vector quantity. Units
Velocity --gt m/s, Acceleration --gt m/s2
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Kinematic Equations

• For a uniformly accelerated motion
• v v0 at
• x ½(v0 v)t
• x v0 t ½at2
• v2 v02 2ax
• x travel distance, a acceleration, v final
  velocity, v0 initial velocity, t travel time.

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Problem
How long will it take a runner, starting from
rest andaccelerating uniformly at 1.5 m/s2, to
travel 3.0 m? A) 21/2 sec B) 1.5 sec C) 2.0
sec D) 3.0 sec
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Freely Falling Bodies
Free fall is motion under the influence of
gravity. When you toss an object in the air it
is in free fall, whether it is going up or down.
Its velocity will decrease as it goes up and
increase as it goes down because the Earth pulls
on it due to its gravity. Close to the surface,
the acceleration due to gravity of the Earth is
about 9.8 m/s2. This means during free fall the
velocity will change by 9.8 m/s every second.
All objects, regardless of their masses, fall at
the same rate on Earth, provided the air drag is
negligible. They all have an acceleration of 9.8
m/s2, vertically down.
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Force and Motion, Gravitation

• Mass, center of mass, weight
• Newtons second law
• Newtons third law
• Law of gravitation
• Uniform circular motion, centripetal force
• Friction
• Inclined planes
• Pulley systems

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Newtons Law of Universal Gravitation
Every body in the universe attracts every other
body with a force that is directly proportional
to the product of the masses of the bodies and
inversely proportional to the square of the
distance between the bodies.
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Centripetal Force
The centripetal force is the net force required
to keep an object of mass m, moving at a speed v,
on a circular path of radius r, and it has a
magnitude of
Direction The centripetal force always points
toward the center of the circle and continually
changes direction as the object moves.
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Satellites in Circular Orbits
Orbital speed is given by,
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Equilibrium and Momentum

• Equilibrium
• Translational equilibrium
• Rotational equilibrium, torques, lever arms
• Newtons first law, inertia
• B. Momentum
• Impulse
• Conservation of linear momentum
• Elastic and inelastic collisions

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Translational equilibrium
For translational equilibrium, the net force
acting on the object must be zero.
The above equation can also be written as,
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Rotational equilibrium
For rotational equilibrium, the net torque acting
on the object must be zero.
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TORQUE and LEVER ARM

• Torque (Magnitude of the force)(Lever arm)
• t Fl
• Direction Counterclockwise OR Clockwise.
• SI Unit of Torque newton meter (N m)

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Problem
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Impulse, J
The impulse J of a force is the product of the
average force and the time interval Dt during
which the force acts
Impulse is a vector quantity and has the same
direction as the average force. SI Unit of
Impulse newton second (N s)
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Momentum, p
The linear momentum p of an object is the product
of the objects mass m and velocity v
Linear momentum is a vector quantity that points
in the same direction as the velocity. SI Unit of
Linear Momentum kilogram meter/second (kg
m/s)
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The Principle of Conservation of Linear Momentum
The total linear momentum of an isolated system
remains constant (is conserved).
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Collisions
Collisions are often classified according to
whether the total kinetic energy changes during
the collision 1.Elastic collisionOne in which
the total kinetic energy of the system after the
collision is equal to the total kinetic energy
before the collision. 2.Inelastic collisionOne
in which the total kinetic energy of the system
is not the same before and after the collision
if the objects stick together after colliding,
the collision is said to be perfectly inelastic.
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Head-on Collision
A 1200-kg car moving east at 15 m/s collides
head-on with a 1500-kg car moving west at 20 m/s.
If the collision is perfectly inelastic, What is
the velocity of the wreckage? A) 4.4 m/s
eastB) 18 m/s east C) 18 m/s westD) 4.4 m/s
west
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Work and Energy

• Work
• Kinetic energy
• Potential energy
• Conservation of energy
• Energy transformations
• Conservative forces
• Power

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Work
The work done on an object by a constant force F
is
F magnitude of the force, s magnitude of the
displacement, and ? angle between the force and
the displacement.
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Kinetic Energy
SI Unit of Kinetic Energy joule (J)
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Work-Energy Theorem
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Gravitational Potential Energy
The gravitational potential energy PE is the
energy that an object of mass m has by virtue of
its position relative to the surface of the
earth. That position is measured by the height h
of the object relative to an arbitrary zero
level
SI Unit of Gravitational Potential Energy joule
(J)
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Problem
How much work is done when a constant horizontal
20-N force pushes a 50-kg block a distance of 10
m on a horizontal surface? A) 50 J B) 100 J
C) 200 J D) 500 J
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Wave Characteristics and Periodic Motion

• Wave characteristics
• Transverse and longitudinal motion
• Wavelength, frequency, velocity, amplitude,
  intensity
• Superposition of waves, phase, interference,
  addition
• Resonance
• Standing waves, nodes
• Beats
• B. Periodic motion
• Hookes law
• Simple Harmonic Motion
• Pendulum motion

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Wave Speed
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Sound

• Production of sound
• Relative speed of sound in solids, liquids, and
  gases
• Intensity, pitch
• Doppler effect
• Resonance in pipes and strings
• Harmonics

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The Doppler Effect
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Standing wave patterns in a Stretched String
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Fluids and Solids

• Fluids
• Density, specific gravity
• Buoyancy, Archimedes principle
• Hydrostatic pressure
• Viscosity
• Continuity equation
• Bernoullis equation
• Turbulence
• Surface tension
• B. Solids
• Density
• Elementary topics in elastic properties

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Electrostatics and Electromagnetism

• Electrostatics
• 1. Charge, charge conservation,
  conductors,insulators
• 2. Coulombs law, electric force
• 3. Electric field
• a. Field lines
• b. Fields due to charge distribution
• 4. Potential difference, absolute potential,
  equipotential lines
• 5. Electric dipole
• B. Electromagnetism
• 1. Magnetic fields
• 2. Electromagnetic spectrum, X-rays

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Coulomb's Law
The magnitude F of the electrostatic force
exerted by one point charge on another point
charge is directly proportional to the magnitudes
q1 and q2 of the charges and inversely
proportional to the square of the distance r
between them.
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The Parallel Plate Capacitor
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Definition of Electric Potential
The electric potential V at a given point is the
electric potential energy EPE of a small test
charge q0 situated at that point divided by the
charge itself
SI Unit of Electric Potential joule/coulomb
volt (V)
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The Force That a Magnetic Field Exerts on a
Moving Charge
The following two conditions must be met for a
charge to experience a magnetic force when placed
in a magnetic field 1.The charge must be moving.
No magnetic force acts on a stationary
charge. 2.The velocity of the moving charge must
have a component that is perpendicular to the
direction of the magnetic field.
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Right-hand Rule No. 1
When the right hand is oriented so the fingers
point along the magnetic field B and the thumb
points along the velocity v of a positively
charged particle, the palm faces in the direction
of the magnetic force F applied to the particle.
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Electric Circuits

• Current
• Batteries, electromotive force, voltage, terminal
  potential, internal resistance
• Resistance, Ohms law, series and parallel
  circuits, resistivity
• Capacitor, dielectrics
• Electric power
• Root-mean-square current and voltage

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Light and Geometric optics

• Visual spectrum, color
• Polarization
• Reflection, mirrors, total internal reflection
• Refraction, refractive index, Snells law
• Dispersion
• Thin lenses, combination of lenses, diopters,
  lens aberrations

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Lens/Mirror Equation and Magnification, m
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Atomic and Nuclear Structure

• Atomic number, atomic weight
• Neutrons, protons, isotopes
• Radioactive decay, half-life
• Quantized energy levels for electrons

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Atomic model
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Nuclear Structure
A Rutherford scattering experiment
Atoms Are Mostly Empty Space
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Bohr Model
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The line spectra for neon and mercury, along with
the continuous spectrum of the sun.
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Hydrogen Spectra
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Radioactivity
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a Decay and the Release of Energy
The decrease in mass is, 238.0508 u 238.0462 u
0.0046 u. 1 u 931.5 MeV The released energy
is 0.0046 x 931.5 4.3 MeV.
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Half-Life
The half-life T1/2 of a radioactive decay is the
time in which one-half of the radioactive nuclei
disintegrate.