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

1. Mechanics 37

1.74. Two loads of the same mass are tied

to the ends of a weightless inextensible

Fig. 37^ Fig. 38

thread passed through a weightless pulley

(Fig. 38). Initially, the system is at rest,

and the loads are at the same level. Then

the right load abruptly acquires a horizon-

tal velocity v in the plane of the figure.

Which load will be lower in a time?

1.75. Two balls of mass m 1 = 56 g and

m 2 = 28 g are suspended on two threads

of length / 1 = 7 cm and / 2 = 11 cm at the

end of a freely hanging rod (Fig. 39).

Determine the angular velocity o at which

the rod should be rotated about the vertical

axle so that it remains in the vertical posi-

tion.

1.76. A weightless horizontal rigid rod along

which two balls of the same mass m can move

without friction rotates at a constant an-

gular velocity co about a vertical axle. The

balls are connected by a weightless spring

of rigidity k, whose length in the undeformed

state is / 0. The ball which is closer to

the vertical axle is connected to it by the

same spring.