Work, Power and EnergyHard
Question
Two identical discs, each of negligible mass and radius r(<<< l) are connected by a uniform rod of mass m and length l as shown in the figure. The disc A is connected with an ideal spring of spring constant k at its centre. The spring is unstretched when θ = 0o. There is no slipping at any contact at any point of time during the motion. Choose the correct statement(s) [Spring always obeys Hook′s Law and mg = k l]. During the motion, each disc remains in contact with the contact surface :-
Options
A.The value of θ, when the system is in stable equilibrium is 60o
B.The value of θ, when the system is in stable equilibrium is 30o
C.Spring potential energy of the system in the state of stable equilibrium is 
D.The angular speed of the rod when it passes through the position of the stable equilibrium is 
Solution
Strech in spring = y
y = l (1 - cos θ)
U =
ky2 + mg 
= 0 ⇒ θ = 60o & 
> 0
y = l (1 - cos θ)
U =
ky2 + mg = 0 ⇒ θ = 60o & > 0Create a free account to view solution
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