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