(Probable) Exam #2 Topics


Newton III                                Pairs

Gravity                                      F=GMm/r2, g=acceleration at earth surface = GM/r2

Orbit                             weightlessness in orbit

Normal Force                             Not always mg.  Compression of material like a spring

Tension                                     Stretching of material like a spring

Friction                                     Non-conservative, Fstatic <= msN, Fdynamic = mdN, ABS

Static Friction                 equals applied force up to Fstatic_max, then breaks free

Sliding (= Kinetic)          Always same once broken free

Free Body Diagrams

Coupled masses                         Airtrack cart and falling weight, monkey, inclined plane

Uniform circular motion             Must accelerate to go in a circle with a = mv2/r.  Loop-de-loop

                                                A force must cause this acceleration.  Rotor ride, vomit comet


Work                                        W=∫F·dx .  Positive if F and dx in same direction.

                                                Dot product: amount of force along motion/motion along force

                                                Change in energy.  Ef = Ei + W

Mechanical Energy                       Conservative/non-conservative forces

Kinetic Energy              Some of individual kinetic energies

Potential Energy            Gravity, springs, easily turned into kinetic energy, not friction

Graphs                           Turning points, F = -dU/dx = -slope of U(x)

Energy transfer                Between kinetic and potential energy

Power                            Energy/time

Conservation                  When is mechanical energy conserved?

Internal Energy                            E = K + Ugravity + Uspring + Uheat + Uchem + Unuclear + mc2 + etc.


Momentum                                vectors, conserved separately each direction

Impulse                                    Impulse = change in momentum, rose, sledge hammer

                                                P conserved if impulse=0:  Fext=0 or tà 0

Padding                         Same impulse, longer time means smaller force

Collisions                                  small time: small impulse: p conserved

Inelastic                         p conserved, E lost:  stuck together is pure inelastic

Elastic                           p conserved, E conserved: How to solve

Center of mass                           How to find, Useful frame of reference

Rocket                                       Newton III or impulse explanation

Relativistic Energy and Momentum

Definitions                                 p=ϒmv, E=ϒmc2, ϒ=1/sqrt(1-v2/c2)

Definition of Kinetic Energy          E=mc2 + K

Workhorse                                 E2 = m2c4 + p2c2

Binding Energy


Physics 190