P101 F10 L16 - SFSU Physics & Astronomy

2y ago
15 Views
3 Downloads
374.99 KB
19 Pages
Last View : 1m ago
Last Download : 2m ago
Upload by : Rosa Marty
Transcription

Lecture 16Midterm 1 ReviewMidterm #1 - Monday Oct. 4About Midterm 1z On Monday, Oct. 4 we will have Midterm Exam 1, whichcovers Hewitt, Chapters 2-8 & 10-14 (Lectures 1-15).z Exam 1 is closed-book, but Equation Sheet 1 will beprovided with the exam.z Bring a scientific calculator with good batteries. (Cellphones, iPads, computers, etc. not allowed.)z Exam 1 will have a multiple-choice section based onquestions taken from lecture example problems,WebAssign problems, and quiz questions.z Exam 1 will have a free-response section based onWebAssign homework problems.1

Midterm #1 - Monday Oct. 4Chap. 2: NEWTON'S FIRST LAW OF MOTION: All sectionsexcept “The Moving Earth”Chap. 3: LINEAR MOTION: All sectionsChap. 4: NEWTON'S SECOND LAW OF MOTION: AllChap. 5: NEWTON'S THIRD LAW OF MOTION: All sectionsChap. 6: MOMENTUM: All but “More Complicated Collisions”Chap. 7: ENERGY: All except “Sources of Energy”Chap. 8: ROTATIONAL MOTION: All but “Simulated Gravity”Chap.10: PROJECTILE AND SATELLITE MOTION: only“Projectile Motion”, “Fast-Moving Projectiles—Satellites”Chap.11: ATOMIC STRUCTURE: All but “Antimatter” and“Dark Matter”Chap.12: SOLIDS: “Density” onlyChap.13: LIQUIDS: All but “Surface Tension” & “Capillarity”Chap.14: GASES: All except PlasmaSummary of Lecture 1z Most physical quantities have units, which must bestated along with the numerical value to give completeanswer.z Fundamental units: length (m), mass (kg), time (s).z Other important units used so far: force (N), energy(J), power (W), and combinations like m/s and m/s2.z All terms in an equation must have the same dimensionsz Convert from one unit to another using fractions ofvalue 1: (2 cm)(1 m/100 cm) 0.02 mz Directions must be specified for vector quantities.2

Key Points of Chapter 2 Newton’s First LawAn object at rest remains at rest and an object inmotion remains in uniform motion* unless a netforce acts on the object.*Moving in a straight line with constant speed. Inertia (measured by mass; unit of mass: kg) Nature of Force; SI Unit of force (N) Combining forces to get net force Equilibrium (zero net force): Motion does not change Fundamental and Practical Forces Normal force (support force)Units of Chapter 3(Linear Motion; Free Fall)1. Distance2. Average Speed and Velocity3. Instantaneous Velocity4. Acceleration5. Motion with Constant Acceleration -Free Fall6. Acceleration of Gravity7. Freely Falling Objects3

Summary of Chapter 3 (1)z Distance d: total length of travelz Displacement d: change in positionz Average speed: distance/time (d/t or d/ t)z Average velocity v d/ t, give directionz Instantaneous velocity: average velocitymeasured over an infinitesimally small timez Relative motion: v13 v12 v23Summary of Chapter 3 (2)z Average acceleration: change in velocitydivided by change in time (a v/ t direction)z Have Acceleration if size or direction ofvelocity is changingz For constant acceleration, distance covered intime t if starting from rest ½at2z Freely falling objects: constant accelerationg 9.8 m/s2 10 m/s2 DOWNWARDORg - 9.8 m/s2 -10 m/s2when upward is considered the positive direction4

Freely Falling ObjectsPositionTrajectory of a projectile:VelocityAccelerationSummary of Chapter 4 (1)nd Law: F ma)(Newton’s 2ndz Force: a push or pullz Mass: measures the difficulty inaccelerating an objectz Newton’s First Law: if the net force on anobject is zero, its velocity is constantz Inertial frame of reference: one in whichthe first law holds (no reference frame accel.)z Newton’s Second Law:5

Summary of Chapter 4 (2)z Forces are vectors. Net force determinesacceleration.z Weight: gravitational force exerted by theEarth on an object. On the surface of the Earth,W mg DOWNWARD (or W - mg)z g 9.8 m/s2 or 9.8 N/kgz Normal force: force exerted perpendicular to asurface by that surfacez Other forces: Tension (as in a rope); frictionSummary of Chapter 5(Newton’s 3rd Law; Vectors)z Newton’s Third Law: If object 1 exerts aforce F on object 2, then object 2 exerts aforce –F on object 1.z Alternate Wording: “For every action there isan equal and opposite reaction.”z The two members of the action/reaction forcepair act on two different objects.6

Summary of Vectorsz Scalar: number, with appropriate unitsz Vector: quantity with magnitude and directionz Magnitude of Vector Sum: A (Ax2 Ay2)1/2z Direction: θ arctan(Ay / Ax)z Graphical (“parallelogram”) vector addition:Net ForceA B(25 Newtons)Force B(10 N)ObjectForce A(20 Newtons)Parallelogram ruleSummary of Chapter 6(Momentum)z Linear momentum:z Momentum is a vectorz Impulse:z Impulse is a vectorz The impulse is equal to change in momentum7

Summary of Chapter 6z Momentum of system is conserved if the netexternal force is zero : pi pfz Internal forces within system always sum tozeroz In collision, assume external forces can beignoredz Inelastic collision: kinetic energy not conservedz Completely inelastic collision: the objects sticktogether afterwardzElastic collision: Kinetic Energy conservedCheck YourselfLarge (4 kg) fish swims at 3 m/s towards a small(2 kg) fish (at rest) and swallows it for lunch.Total momentum before lunch?Total momentum after lunch?Velocity of the large fish (with small fish inside)?8

Summary of Chapter 7(Work & Energy)z Work is force times distance moved indirection of force.W Fdz SI unit of work: the joule (J)z Power is the rate at which work is done:z SI unit of power: the watt (W): 1 W 1J/sWorkDefine work W done on an object by a force F as(Work) (Force) X (Distance parallel to force)W F dSI Unit of Work: Joule (J)d is distance along force directionForce acting in direction of motion: Positive work.Force acting in opposite direction: Negative work.Force perpendicular to motion: Zero work9

Gravitational Potential EnergyGravitational potential energy of an object is(Potential Energy) (Weight) x (Height)PE m g h mghwhere m is mass of object in kg, h is heightof object in m, and g 9.8 N/kg 9.8 m/s2Choose h 0 to be at a convenient placeKinetic Energy (KE)Energy associated with motion.Kinetic energy of an object is(Kinetic Energy) ½ x (Mass) x (Speed)2KE ½ m v2where m is mass of object in kg and v isspeed in m/s.A stationary object has zero kinetic energy.Kinetic energy is never negative.10

Conservation of Mechanical EnergyDefinition of mechanical energy E:E KE PEIf the only work done in going from the initial tothe final position is done by gravity or springs:When only gravity orspring forces actOr equivalently:Nonconservative ForcesIn the presence of nonconservative forces(friction, motors, person), the total mechanicalenergy is not conserved.The work done by non-conservative forces equalsthe change in mechanical energy. E PE PE WNC11

Example: Friction Work E You (mass 50 kg) are skiing at 10 m/s on aflat frictionless surface. What is your KE?KE ½mv2 ½ (50 kg)(10 m/s)2 2500 J You dig your poles into the snow, causing afriction force of 100 N. What work doesfriction do if it stops you? What distance will you travel beforestopping?Chapter 8 - Rotational MotionAvg. Angular Velocity # Revolutions/(Time Taken)ω θ / tUnit: Revolutions/s or Revolutions/min (RPM)Sign convention : ω is positive for counterclockwiserotation, negative for clockwise rotationExample: Wheel turns CCW through 60 revolutionsin 2 minutes. What is the rotational speed?ω 60 Rev/(2 min) 30 RPM or 0.5 rev/s12

Translational vs. Rotational SpeedEvery point on a rotating body has an angularvelocity ω and a tangential velocity vt.vt d/ t 2πR( θ)/ t 2πRωvtdRCentripetal ForceWhenever an object moves along a circular path,there must be a force on that object in the directionof the center of the circle -- Centripetal ForceAmount of centripetalforce needed is largewhen Speed is large Radius is small Mass is large30-Sep-1013

Torque and Rotational Inertiaz A force applied so as to try to cause angularacceleration is said to exert a torque. Positivetorque trys to cause Counterclockwise rotation.z Rotational Inertia I measures object’s resistance tochange in rotational motion. Rotational inertia isgreater when mass is farther from rotation axis.z Torque: τ F (lever arm) ( distance from lineof force to axis)z In order for object to be in equilibrium, thetotal force and the total torque acting on theobject must both be zero.Balance of TorquesTorques clockwise and counter-clockwisebalance in both cases since(250 N) x (3 m) (500 N) x (1.5 m)30-Sep-10Her lever armis still 3 meters14

Angular Momentumz Angular momentum:z Changing an object’s angular momentumrequires a net torque: L τ tz In systems with no external torque, angularmomentum is conserved : Lf Li(or Iiωi Ifωf )z Example: Ice skater is rotating at 0.5 rev/s. Shemulls in her arms to reduce her rotational inertia bya factor of three. What will be her new rotationalspeed? (ωf (Ii/If)ωi (1/(1/3)) (0.5 rev/s) 1.5 rev/s)Center of Mass/GravityAverage position of all the mass in an objectis called the Center of Mass (CM) orCenter of Gravity (CG) of object.Force of gravity can be considered to act atthe CG of an object.The lever arm for gravitational torque goesfrom the CG to the rotation axisAn object is stable if its CG lies over thesupport base.30-Sep-1015

Periodic Motion CharacteristicsPeriod T: time required for one cycle ofperiodic motion (unit: s)Frequency f: number of cycles per unit timeThe frequency unit iscalled a Hertz (Hz):Amplitude A: maximum distance objectmoves from equilibrium (unit: m)Chapter 10 - Projectile MotionProjectile motioncombinesuniformhorizontalmotion (constanthorizontalvelocity) withfreefall verticalmotion(vertical accel. -9.8 m/s2).16

Distance FallenThe distance fallenis the samewhether fallingstraight down orin projectilemotion.Vertical distancefallen: d ½gt2 iffalling from rest.0.5 s5 meters1.0 s1.5 s30-Sep-10Chap. 11 - Atomic StructureAn atom is composed of nucleus– concentration of nearly all the atom mass– made up of protons (positive electric charge) andneutrons (no electric charge)– Very, very small ( 10-14 m) electrons––––even smaller than nucleus2000 times less massive than nucleusnegative electric charge (same amount as proton)may be thought of as “orbiting” nucleus Number of electrons in atom equal to number ofprotons in nucleus, so atom has no net charge17

IsotopesCHECK YOURSELFA nucleus with an atomic number of 44 and a mass numberof 100 must haveA.B.C.D.44 neutrons.56 neutrons.100 neutrons.All of the above.Chapter 12-13 - Density & Fluids Density:SI Unit: kg/m3 Pressure:SI Unit: Pa N/m2 Atmospheric pressure: 101 kPa 101000 Pa Gauge pressure: Pressure with depth:18

Summary of Chapter 13 Archimedes’ principle: Object completelyimmersed in a fluid experiences an upwardbuoyant force equal in magnitude to the weightof fluid displaced by the object.FB ρfgVsub Equation of continuity for liquids:A1v1 A2v2 Pascal’s Principle: Change in Pressure at onepoint in fluid transmitted to all points in fluidSummary of Chapter 14(Gases) Atmospheric pressure: 101 kPa Gauge pressure: Pressure versus volume: (P1V1 P2V2)(“Boyle’s Law; for constant temperature) Bernoulli’s effect: Pressure is lower in amoving fluid than in a static fluid. The greaterthe fluid velocity, the lower the pressure in themoving fluid.19

Chap.10: PROJECTILE AND SATELLITE MOTION: only “Projectile Motion”, “Fast-Moving Projectiles—Satellites” . Chapter 10 - Projectile Motion Projectile motion combines uniform horizontal motion (constant horizontal velocity) with freefall vertical motion (vertical accel. -9.8 m/s2). 17 30-Sep-10 Distance Fallen

Related Documents:

Oct 01, 2020 · F10.130 - Alcohol abuse with withdrawal, uncomplicated F10.131 - Alcohol abuse with withdrawal delirium F10.132 - Alcohol abuse with withdrawal with perceptual disturbance F10.139 - Alcohol abuse with withdrawal, unspecified F10.930 - Alcohol use, un

SFSU Faculty Advisor: Dr. Kimberly D. Tanner (Spectrum Program) Project #13: Girls Inspiring Science SFSU Undergraduate Student: Sara Bravo (Microbiology) SFSU Post-Bac: Reyna Menjivar (Biology) SSFUSD Teacher: Jocelyn Ting, Parkway Heights Middle School SFSU Faculty Advisor: Dr. Kimberly D. Tanner (Spectrum Program)

Physics 20 General College Physics (PHYS 104). Camosun College Physics 20 General Elementary Physics (PHYS 20). Medicine Hat College Physics 20 Physics (ASP 114). NAIT Physics 20 Radiology (Z-HO9 A408). Red River College Physics 20 Physics (PHYS 184). Saskatchewan Polytechnic (SIAST) Physics 20 Physics (PHYS 184). Physics (PHYS 182).

The installation of the tracks onto the mast can be split in 5 steps: 6- Preparation of the slugs 7- Fitting the top track 8- Fitting the standard tracks (F10-20-30 / 2m ou F40 / 1.70m) 9- Fitting the loading track (F10-20-30 / 0.35m ou F40 / 0.33m) 10- Tigh

F10 Product Price List F10.r2 Effective January 1, 2020 1-574-295-8330 www.elkhartbrass.com

Advanced Placement Physics 1 and Physics 2 are offered at Fredericton High School in a unique configuration over three 90 h courses. (Previously Physics 111, Physics 121 and AP Physics B 120; will now be called Physics 111, Physics 121 and AP Physics 2 120). The content for AP Physics 1 is divided

16.07 Dynamics Fall 2008 Version 1.1 Lecture L16 - Central Force Motion: Orbits In lecture L12, we derived three basic relationships embodying Kepler’s laws: Equation for the orbit trajectory, r h2/µ a(1 e2) . (1) 1 e cos θ 1 e cos θ elliptical orbits

Engineering Mathematics – I, Reena Garg, Khanna Book Publishing . AICTE Recommended Books for Undergraduate Degree Courses as per Model Curriculum 2018 AICTE Suggested Books in Engineering & Technology w.e.f. 2018-19 BSC103 – Mathematics – II 1. Advanced Engineering Mathematics, Chandrika Prasad & Reena Garg, Khanna Book Publishing 2. Higher Engineering Mathematics, Ramana B.V., Tata .