I need help to take the time derivative of a physics equation.(adsbygoogle = window.adsbygoogle || []).push({});

The equation:

ME=1/2 mr^2 (dθ/dt)^2 +mgr θ^2/2

Where ME is the mechanical energy , m is the mass of the object, r is the radius of the path of the object and θ is the angle around the path.

Walter Lewin at MIT differentiates it and gets the result:

mr^2 (dθ/dt) (d^2 θ/dt^2)+mgr θ dθ/dt

Can someone please explain why this is so. I can't understand how that would be the derivative of the function. Please answer.

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# Help required to differentiate a function.

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