MomentumOr, “How to make Newton’s

Laws even more complicated without even trying…”

Daryl L TaylorGreenwich HS, CT

©2004, 2006, 2007, 2009, 2012 (Just in case…)

Nitty Gritty?

Definitions?

•‘member FMA?

F ma

vF m

t

Ft m v

Ft mv

F ma

ImpulseLatin impulsus, from past participle of impellere, to impelImpel: See impulse…

MomentumLatin mōmentum, movement

Nitty Gritty?

Definitions?

•P Conservation

' '1 1 2 2 1 1 2 2

i fP P

m v m v m v m v

Why?

1 2

1 1 2 2

1 1 2 2

1 1 2 2

F F

m a m a

m v m v

t tm v m v

POP QUIZ;

#1

2-D Momentum

Momentum is a linear vector

1 2

1 1 2 20 0m v m v

2-D Momentum

Angles?

m1v1i

2-D Momentum

Angles?

m1v1i

m1v1f

m2v2f

2-D Momentum

Angles?

m1v1i

m1v1f

m2v2f

POP QUIZ;

#2

2.5 m/s

Types of Collisions;

•Elastic AND KE are conserved

i f

i fKE KE

Types of Collisions;

•Inelastic ONLY are conserved

i f

POP QUIZ;

#3

MV & cm

cm• Center of Mass

NOT to be confused with Center of Gravity (cg)

MV & cm

cm• Examples

MV & cm

Cm• Examples

MV & cm

cm

MV & cm

Cm – Hume Beans• Bending over• Sitting• Standing• Walking• One-Leg Lift (Wall & Free-standing)• Butt against wall – Touch toes• Chair pick-up• Babies vs Adults

Head size – ¼ vs 1/8

MV & cm

Cm – Hume Beans• Wile E. Coyote Video• m-stick and hat• Rolling UP HILL demo