Momentum & energy

Momentum P = mv Momentum is mass in motion Vector quantity Dimensions?

Force & Momentum Force is the derivative of momentum as

a function of time. F = ∆P/∆t = m∆v/∆t Of course ∆v/∆t is accel.

Momentum Conservation The momentum of a system is always

conserved. Complication - P is a vector qty. - which

means we will have vector considerations when working w/ P conservation.

Po = Pf Like relative velocity we have to create the

exact formula based on the specific circumstance.

Scenarios for P conservation Explosion Po = P1 + P2 +…. + Pn ; exact formula depends on # of pcs. before & after. Collisions --> Explosion P1o + P2o = P1f + P2f ; exact formula depends on # of pcs. before & after Collision --> Coalescence P1o + P2o = Pf ; typically here only 2 pcs. collide, see problem #13, p.238

Energy Exist in 7 forms - crimsen --> cr(h)msen Can be transferred - always involves

same form of energy. Can be transformed - involves more

than 1 form. Scalar quantity Energy is defined as the ability to do

work. Discuss implications.

Mechanical Energy 2 forms 1) kinetic, 2) potential Ek = 1/2mv2

Ep = mgh

Work W = Fd W = ∆Ek

W = ∆Ep

Work like E is a scalar quantity?? Fig. 10-2, p. 258

Energy Conservation The energy of a system is always conserved. Complication - 7 forms of energy & 2 forms of

mech. E. Elastic collision - mech. E conserved Inelastic collision - mech. E is not conserved. Falling body - Epo = Ekf

Exact form of E conservation eq. Is circumstance dependent.

P & E conservation Occurring to every system @ the same

time. Complicated b/c P is vector & E is

scalar & b/c energy exist in 7 forms.