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- Homework Statement
- The torsional spring at A has a stiffness of

k = 2000 N /rad and is uncoiled when theta = 0°. Determine

the angular velocity of the bars, AB and BC, when theta= 0°, if

they are released from rest at the closed position, theta = 90°.

The bars have a mass per unit length of 20 kg/m.

- Relevant Equations
- conservation of energy

Hello,

so we have two potitions right, if we take ##\theta = 90## as the first position (i.e. both rods are flat) and then the second position at ##\theta = 0##.

I totally understand the exercise, not difficult. The only issue I am having is the torsional spring... it says that it is uncoiled at 0 degrees. Does this mean that the potential energy at position 2 is at maximum?

Because if so I get a negative value from which I need to find ##\omega_{AB}## which is of cousre not possible.

this is the eq. by conservation of energy:

##T_1 + V_1 = T_2 + V_2## note: angular velocity of BC is zero ! that is why there is only one term.

##0 + 0 + = 450*\omega_{AB}^2 + \frac122000*(\pi/2)^2 + 2060.1##

##\omega_{AB}^2 = -...... ##

Which is not possible. And from this I know that the elastic potential energy needs to be at the other side, but the question is why is the EPOT maximum at position 1 i.e. theta = 90 degrees as it says that it is uncoiled at theta = 0 degrees?

Thanks in advance.!