#  Chapter 11: Rotational Dynamics and Static Equilibrium Ch11-1 Torque

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 Chapter 11: Rotational Dynamics and Static Equilibrium Ch11-1 Torque
CCW +

Applying a Torque

Ct1: You are using a wrench and trying to loosen a rusty nut
Ct1: You are using a wrench and trying to loosen a rusty nut. Which of the arrangements shown is least effective in loosening the nut? A B C D

Chapter 11: Rotational Dynamics and Static Equilibrium
Ch11-1 Torque  = rF = rFsin

Chapter 11: Rotational Dynamics and Static Equilibrium
Torque = moment arm x force = rF = rsinF The moment arm is the perpendicular distance from rotation axis to the line of action of the force. moment arm line of action of the force

P11.2 (p.350)

  = I Torques summed about fixed axis O.
Chapter 11: Rotational Dynamics and Static Equilibrium CCW + Ch11-2 Torque and Angular Acceleration  = I Torques summed about fixed axis O. P11.15 (p.351)

CT2: Two wheels with fixed hubs, each having a mass of 1 kg, start from rest, and forces are applied as shown. Assume the hubs and spokes are massless, so that the rotational inertia is I = mR2. In order to impart identical angular accelerations, how large must F2 be? A N B. 0.5 N C. 1 N D. 2 N E. 4 N

 Chapter 11: Rotational Dynamics and Static Equilibrium
CCW + Ch11-3 Zero Torque and Static Equilibrium F = 0 and  = P11.22 (p.351)

CT3: P11.22c If the mass of the teeter-totter were doubled, the answers to parts a and b for the position of the applied force would double. halve. stay the same.

P11.31 (p.352)

Chapter 11: Rotational Dynamics and Static Equilibrium
Ch11-4 Center of Mass and Balance Near the Earth, the center of mass is the balance point of an object.

Chapter 11: Rotational Dynamics and Static Equilibrium
Ch11-5 Dynamic Applications of Torque We can finally relax the simplification that a pulley is massless P11.44 (p.353)

CT4: P11.44a The 25N tension is greater than the tension on the other side. less than the tension on the other side. the same as the tension on the other side.

Chapter 11: Rotational Dynamics and Static Equilibrium
Ch11-6 Angular Momentum p = mv (kgm/s) L = I (fixed axis) (kgm2/s) F = p/t  = L/t P11.55 (p.353)

Chapter 11: Rotational Dynamics and Static Equilibrium
Ch11-7 Conservation of Angular Momentum If Fext = 0, then ptot is conserved If  = 0, then Ltot is conserved P11.63 (p.354)

Chapter 11: Rotational Dynamics and Static Equilibrium
Ch11-8 Rotational Work and Power W = Fx =  (one dimension or fixed axis) W = K Power = W/t = /t =  P11.68 (p.354)

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