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Experiment 3-4: Rotational Dynamics, Angular Momentum

8.01

W10D2

Today’s Reading Assignment: MIT 8.01 Course Notes

Chapter 17 Two Dimensional Rotational Dynamics Worked Example 17.11-17.12

Chapter 19 Angular Momentum Sections 19.7-19.9, Worked Example 19.8

Announcements

Hand in your answers to today’s reading questions at the end of the class. Problem Set 8 due Week 11 Tuesday at 9 pm in box outside 26-152 Math Review Week 11 Tuesday at 9 pm in 26-152 Exam 3 Tuesday Nov 26 7:30-9:30 pm Conflict Exam 3 Wednesday Nov 27 8-10 am, 10-12 noon Nov 27 Drop Date

Rotor Moment of Inertia

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Conservation of Angular Momentum

•  Assumption: all internal torques cancel in pairs

•  Rotational dynamics

•  No external torques

•  Change in Angular momentum is zero

•  Angular Momentum is conserved

sysext SSS

ddt

= L

τ

ΔLS

sys ≡LS , f

sys −LS ,i

sys =0

sysext SSS

ddt

= = L0

τ

LS , f

sys =LS ,i

sys

3

Angular Impulse and Change in Angular Momentum

•  Angular impulse

•  Change in angular momentum

•  Rotational dynamics

ΔLS

sys ≡LS , f

sys −LS ,i

sys

τSS

ext dtti

t f

∫ =LS , f

sys −LS ,i

sys

ext sysave int( )SS St= Δ = ΔJ L

τ

extf

i

t

SSt

dt= ∫J τ

Experiment 3/4: Moment of Inertia and Conservation of

Angular Momentum