Angular Impulse Angular Impulse = ∑M∆t = ∆H = I∆(omega) Net Angular Impulse: net moment (torque) acting during time interval; the effect of a moment on a system.

= Change in MOMENTUM Momentum – amount of motion a body possesses

Angular momentum - amount of angular motion a body possesses; "H" Impulse creates momentum and vice versa. Jenny, Michelle, and Dale present... What is angular impulse? ∑F = ma

where a = ∆v/∆t

so… ∑F = m(∆v/∆t)

multiply each side by ∆t . . .

∑F∆t = m∆v Linear impulse

The Rotational Equivalent is

∑M∆t = Icm(omega) Purpose:

1) Understand angular impulse - momentum relationship

2) Calculate moments and plot moment-time curves

3) Know that impulse = area under moment-time curve Net Impulse = Change in Momentum (for linear and angular quantities) How did we get this from Newton's Law ∑F = ma? Methods:

Calculate Moments:

1) Use TBCM coordinates (delta x, delta y) to estimate COP location

2) Force x perpendicular distance

=Moment

3) Plot moment-time curves

4) Integrate to find angular impulse. RESULTS ----------------------> Analysis: Post Lab Questions #1-6 Analysis: Post Lab Questions etc. 7) Reduce Horiz RF during Reverse = Risk Inability to Clear Platform

8) Not during all 3 phases. Back requires larger linear impulse (in horiz and vertical direction) to create enough air time for back flip = Back Diver has greater loading time and greater loading forces (see left)

9) No; mechanical objectives of Back and BT differ (see Fig. 2):

BT: translate backward

Back: translate backward, flip backward

10) Yes (Fig. 1). But Reverse must generate more impulse because diver requires greater horizontal force to clear platform. Greater force generation in same amount of time = Greater Impulse.

Mechanical Objectives: BT: translate backward

Back: translate backward, rotate backward

Reverse: translate forward, rotate backward

COP is in front of TBCM for each dive = facilitates torque to create BACKFLIP. 12) Reduce vertical RF during Back Dive = not enough air time to complete backflip. Also, less vertical RF = less vertical impulse = less angular momentum for the flip.

13) Reduce vertical RF during Reverse = not enough air time to complete back flip and "straighten out" = UGLY. BW BW Rv Rv smaller Rv = smaller moment = smaller quantity of rotational motion (momentum)...

same horiz braking force has greater influence to oppose intended moment sucky backflip. vs. Rh Rh Muchas gracias for listening!

Comments? Questions?

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# The Wheels on the Bus Go: Angular Impulse & Momentum

D. Ello, M. Degraaff, J. Nguyen

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