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MCAT PHYSICS REVIEW January 30, 2006 Dr. Ponn Maheswaranathan (Mahes) Office: Sims 213-B, Phone: 323 4940 Office Hours: M and.

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Presentation on theme: "MCAT PHYSICS REVIEW January 30, 2006 Dr. Ponn Maheswaranathan (Mahes) Office: Sims 213-B, Phone: 323 4940 Office Hours: M and."— Presentation transcript:

1 MCAT PHYSICS REVIEW January 30, 2006 Dr. Ponn Maheswaranathan (Mahes) Office: Sims 213-B, Phone: Office Hours: M and W 10-11:50. Maheswaranathan

2 Online Resources Cutnell and Johnson Giancoli 092/http://www.geocities.com/CollegePark/Union/5 092/ view/MainPage.htmhttp://www.udayton.edu/~premed/UCMCATRe view/MainPage.htm

3 Major Physics Topics 1.Translational Motion 2.Force and Motion, Gravitation 3.Equilibrium and Momentum 4.Work and Energy 5.Wave Characteristics and Periodic Motion 6.Sound 7.Fluids and Solids 8.Electrostatics and Electromagnetism 9.Electric Circuits 10.Light and Geometric Optics 11.Atomic and Nuclear Structure

4 Translational Motion A.Units and dimensions B.Vectors: Components and addition C.Speed, velocity, and acceleration D.Freely falling bodies

5 Units and dimensions TimeLengthMass CGSscmg SIsmkg BE/USCsftslug Systems of units CGS-- Centimeter, gram, and second SI----- The international system BE/USC-- British Engineering or the US customary

6 SI Base Quantities and Units Physical Quantity Unit NameSymbol Timeseconds Lengthmeterm Masskilogramkg Electric currentampereA TemperaturekelvinK Amount of substance molemol Luminous intensity candelacd

7 Significant Figures A radar signal is sent from Earth to a planet which is 7 x 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

8 Vectors and Scalars Physical quantities are divided into vectors and scalars. Scalars have magnitude or size only. Vectors have magnitude and direction. ScalarsVectors MassWeight DistanceDisplacement SpeedVelocity Time, Length,Area, Volume,Density, Energy,Power,etc. Acceleration, Force Momentum, Impulse, etc.

9 Components of a Vector Use Cosine for Adjacent component and Sine for opposite component.

10 Vector Addition Example problem: Locating a lost plane

11 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.

12 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 --> m/s, Acceleration --> m/s 2

13 Kinematic Equations For a uniformly accelerated motion: v = v 0 + at x = ½(v 0 + v)t x = v 0 t + ½at 2 v 2 = v ax x = travel distance, a = acceleration, v = final velocity, v 0 = initial velocity, t = travel time.

14 Problem How long will it take a runner, starting from rest and accelerating uniformly at 1.5 m/s 2, to travel 3.0 m? A) 2 1/2 sec B) 1.5 sec C) 2.0 sec D) 3.0 sec

15 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/s 2. 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/s 2, vertically down.

16 Force and Motion, Gravitation A.Mass, center of mass, weight B.Newton’s second law C.Newton’s third law D.Law of gravitation E.Uniform circular motion, centripetal force F.Friction G.Inclined planes H.Pulley systems

17 Newton’s 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.

18 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.

19 Satellites in Circular Orbits Orbital speed is given by,

20 Equilibrium and Momentum A.Equilibrium 1.Translational equilibrium 2.Rotational equilibrium, torques, lever arms 3.Newton’s first law, inertia B. Momentum 1.Impulse 2.Conservation of linear momentum 3.Elastic and inelastic collisions

21 Translational equilibrium For translational equilibrium, the net force acting on the object must be zero. The above equation can also be written as,

22 Rotational equilibrium For rotational equilibrium, the net torque acting on the object must be zero.

23 TORQUE and LEVER ARM Torque = (Magnitude of the force)×(Lever arm)  = F×l Direction: Counterclockwise OR Clockwise. SI Unit of Torque: newton · meter (N · m)

24 Problem

25 Impulse, J The impulse J of a force is the product of the average force and the time interval  t 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)

26 Momentum, p The linear momentum p of an object is the product of the object’s 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)

27 The Principle of Conservation of Linear Momentum The total linear momentum of an isolated system remains constant (is conserved).

28 Collisions Collisions are often classified according to whether the total kinetic energy changes during the collision: 1.Elastic collision—One in which the total kinetic energy of the system after the collision is equal to the total kinetic energy before the collision. 2.Inelastic collision—One 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.

29 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 east B) 18 m/s east C) 18 m/s west D) 4.4 m/s west

30 Work and Energy A.Work B.Kinetic energy C.Potential energy D.Conservation of energy E.Energy transformations F.Conservative forces G.Power

31 Work The work done on an object by a constant force F is: F = magnitude of the force, s = magnitude of the displacement, and θ = angle between the force and the displacement.

32 Kinetic Energy SI Unit of Kinetic Energy: joule (J)

33 Work-Energy Theorem

34 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)

35 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

36 Wave Characteristics and Periodic Motion A.Wave characteristics 1.Transverse and longitudinal motion 2.Wavelength, frequency, velocity, amplitude, intensity 3.Superposition of waves, phase, interference, addition 4.Resonance 5.Standing waves, nodes 6.Beats B. Periodic motion 1.Hooke’s law 2.Simple Harmonic Motion 3.Pendulum motion

37 Wave Speed

38 Sound A.Production of sound B.Relative speed of sound in solids, liquids, and gases C.Intensity, pitch D.Doppler effect E.Resonance in pipes and strings F.Harmonics

39 The Doppler Effect

40 Standing wave patterns in a Stretched String

41 Fluids and Solids A.Fluids 1.Density, specific gravity 2.Buoyancy, Archimedes’ principle 3.Hydrostatic pressure 4.Viscosity 5.Continuity equation 6.Bernoulli’s equation 7.Turbulence 8.Surface tension B. Solids 1.Density 2.Elementary topics in elastic properties

42 Electrostatics and Electromagnetism A.Electrostatics 1. Charge, charge conservation, conductors,insulators 2. Coulomb’s 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

43 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 q 1 and q 2 of the charges and inversely proportional to the square of the distance r between them.

44 The Parallel Plate Capacitor

45 Definition of Electric Potential The electric potential V at a given point is the electric potential energy EPE of a small test charge q 0 situated at that point divided by the charge itself: SI Unit of Electric Potential: joule/coulomb = volt (V)

46 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.

47 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.

48 Electric Circuits A.Current B.Batteries, electromotive force, voltage, terminal potential, internal resistance C.Resistance, Ohm’s law, series and parallel circuits, resistivity D.Capacitor, dielectrics E.Electric power F.Root-mean-square current and voltage

49 Light and Geometric optics A.Visual spectrum, color B.Polarization C.Reflection, mirrors, total internal reflection D.Refraction, refractive index, Snell’s law E.Dispersion F.Thin lenses, combination of lenses, diopters, lens aberrations

50 Lens/Mirror Equation and Magnification, m

51 Atomic and Nuclear Structure A.Atomic number, atomic weight B.Neutrons, protons, isotopes C.Radioactive decay, half-life D.Quantized energy levels for electrons

52 Atomic model Atomic ParticleChargeMass Electron –1.6  C9.11  Kg Proton +1.6  C1.673  Kg Neutron  Kg

53 Nuclear Structure A Rutherford scattering experiment Atoms Are Mostly Empty Space

54 Bohr Model

55 The line spectra for neon and mercury, along with the continuous spectrum of the sun.

56 Hydrogen Spectra

57 Radioactivity

58  Decay and the Release of Energy The decrease in mass is, u – u = u. 1 u = MeV The released energy is = x = 4.3 MeV.

59 Half-Life The half-life T 1/2 of a radioactive decay is the time in which one-half of the radioactive nuclei disintegrate.


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