Time derivative using the quotient rule

[Mishal0488]

Hi Guys

Sorry for the rudimentary post. I am busy with a numerical solution to a mechanics problem, and the results are just not as expected. I am re-checking the mathematics to ensure that all is in order in doing so I am second guessing a few things

Referring to the attached scan, is the quotient rule used correctly when taking the time derivative of the function? Note that both "r" and "theta" are time dependent.

Thanks in advance

 

[PeroK]

Looks right.