(Probable) Exam #2 Topics

Forces

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, F_static <= m_sN, Fdynamic = m_dN, ABS

Static Friction                 equals applied force up to F_{static_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

Energy

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.  E_f = E_i + 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 + U_gravity + U_spring + U_heat + U_chem + U_nuclear + mc² + etc.

Momentum

Momentum                                vectors, conserved separately each direction

Impulse                                    Impulse = change in momentum, rose, sledge hammer

                                                P conserved if impulse=0:  F_ext=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