A mass is winded via string aroung a flywheel and allowed to fall a specific height before detachement. The flywheel is connected to a small DC motor via gears and starts generating electricity once the mass is allowed to fall..(adsbygoogle = window.adsbygoogle || []).push({});

Now without the DC motor ( generator) the equation of energy balance is:

mgh = (0.5mv^2+ (0.5Iω^2) + ( 0.5Iω^2 x (n1/n2)

where I is the moment of inertia of flywheel and ω is the angular velocity ( which should be equal to the angular max velocity at point of mass detachment)

n1 = number of revs of flywheel before detachement of mass

n2 = number of revs of flywheel after detachement

the third term in the equation is the work done to overcome friction.

Now the question is :

What form is the equation going to have when a DC motor is attached to the flywheel to be allowed to transform rotational energy to electrical? mgh = ?

the electrical energy is in the form of UIt

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# Energy balance from mechanical to electrical energy

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