E. Circular Motion II

Homework

 

8.1 Rigid Bodies and Rotations

5, 10, 13

10:vcm = rwsolve for w

13:a = at/r†† solve for a.Next, w2 = wo2 + 2aqwhere you solve for q

 

 

8.2Torque, Equilibrium, Stability

14, 18, 19, 24, 30, 31

 

14:Look at figure 8.5 c on p. 256 and youíll see SF = 0 but the St doesnít = 0

18:When the force is applied ^ to the length of the wrench, minimum force is required and the lever arm equals the length of the wrench.At q = 90o, r^= 0.15 m

††††††††††† t = Fr^ solve for F

19:In this case, r^ = 0.15 sin 30.Use formula from 18 and again solve for F.

24:St = 0.Donít forget that to find distances you must subtract from the designated pivot point.

30:see example 8.5 on p. 259

31:Choose where the string acts as the axis and work from the bottom up.Realize that St must = 0 since they arenít rotating.

 

Even Answers:

10:1.7 rad/s

14:b

18:1.7 x 102 N

24:a:83.3 cm††††† b.62.5 g

30:2.1 x 102 N