18 solution q. E. D

Ans:
v
AB
=
3.70 rad
>
s

---

976
© 2016 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently 
exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 
18–62.
The 50-lb wheel has a radius of gyration about its center of
gravity G of
If it rolls without slipping,
determine its angular velocity when it has rotated clockwise
90° from the position shown. The spring AB has a stiffness
and an unstretched length of 0.5 ft. The wheel
is released from rest.
k
=
1.20 lb/ft
k
G
=
0.7 ft.
SOLUTION
Ans.
v
=
1.80 rad s
+
1
2
(1.20)(0.9292
-
0.5)
2
0
+
1
2
(1.20)[
2
(3)
2
+
(0.5)
2
-
0.5]
2
=
1
2
[
50
32.2
(0.7)
2
]
v
2
+
1
2
(
50
32.2
)(1
v
)
2
T
1
+
V
1
=
T
2
+
V
2
G
B
A
k
= 1.20 lb/ft
3 ft
1 ft
0.5 ft
0.5 ft
Ans:
v
=
1.80 rad
>
s

---

977
© 2016 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently 
exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 
18–63.
The system consists of 60-lb and 20-lb blocks A and B,
respectively, and 5-lb pulleys C and D that can be treated as
thin disks. Determine the speed of block A after block B has
risen 5 ft, starting from rest. Assume that the cord does not
slip on the pulleys, and neglect the mass of the cord.
SOLUTION