Aptitude Test Problems in Physics Science for Everyone by S Krotov ( PDFDrive.com )

Solutions

139

1.38*. It can easily be seen that the ball attains

the equilibrium position at an angle a of deflection

of the thread from the vertical, which is determined

from the condition

μv

tan a.

mg '

During the oscillatory motion of the ball, it will
experience the action of a constant large force

F = (mg)a (μv) 2 and a small drag force
(Fig. 148). Consequently, the motion of the ball

F

Fig. 148

will be equivalent to a weakly attenuating motion
of a simple pendulum with a free-fall acceleration
g' given by

g, g g 1 ( (Rur

cos a^ mg

---g1/-1+(

g

11 -) 2

m