HK 11
 

Pg. 260 - 50, 56, 62, 66*,71, 74*, 76, 79*, 82, 86


50
I = SIi 
mass A + mass B + 2 rods + axis shift for rod 1 + axis shift for rod 2

= 5ml2 +Ml2(1/6 + 1/4 + 9/4)
56
From table (page 249) inertia of a slab around a central axis is 1/12M(a2 + b2 )
From parallel axis theorem I = 1/12 (a2 + b2 ) + M(displacement of axis)2 = 1/12M(a2 + b2 ) + 
62
70*9.8*0.4

71
F = 0.5t + 0.30t2 so t = St = Fr = (0.5t + 0.30t2)*r
St = Ia so a = St / I = (0.5t + 0.30t2)*r /I a(3) = (0.5*3 + 0.3*9)*0.1 / 10-3
w(t) = w( 0 ) + 

76
a) Q = 1/2 a t2 so a = 2Q /t2 and w = 2Q /t
b) a = a*R
c) lower: Mg - TL = Ma so TL = M(g - a)
d) upper: TU - fk = Ma = M a R can be used to find fk = TU- M a R
during time t the mass M makes distance d = Q *R . Energy of system will be smaller by fk Q R
Mg Q R - fk Q R = 2*[1/2 M(2Q R /t)2 ] + I(2Q /t)2 ( two masses M move with speed v = w R and the pulley rotates )
finally: Mg Q R - (TU- M a R)Q R = 2*[1/2 M(2Q R /t)2 ] + I(2Q /t)2

TU = [- 2*[1/2 M(2Q R /t)2 ] - I(2Q /t)2 + Mg Q R ] / Q R + M a R