(^128) Aptitude Test Problems in Physics
From the condition of inextensibility of the rod
B 2 A 2 , it follows that
, 7t V 17. 2
VB2 A2 f = V S111 =-
(^4 6)
We can find the velocity of point B2 relative to a
stationary reference frame by using the cosine law:
2B = v 2 4 + v're 2 (
2 \ 17
v
2 a.2 2 vALVB2= 37112 'V VP^
B2 6 V.1.26. If the thread is pulled as shown in Fig. 142,
the bobbin rolls to the right, rotating clockwise
about its axis.
For point B, the sum of the projections of veloc-
ity vo of translatory motion and the linear veloc-
ity of rotary motion (with an angular velocity o.))
on the direction of the thread is equal to v:v = vo sin a — car.Since the bobbin is known to move over the hori-
zontal surface without slipping, the sum of the
projections of the corresponding velocities for
point C is equal to zero:vo — wR = 0.