# MATLAB Using Matlab to solve dynamics problem

#### spin360

I've attached my problem set. I'm having an issue on how to write the formula to insert it into matlab. According to the problem set, dl/dt = 0.2m/s. I actually have the "solution" to the problem, though I don't understand why the answer is what it is. Basically, my instructor used the pythagorean theorem and set l$$^{2}$$ = b$$^{2}$$ + $$^{2}$$. He then differentiated twice w.r.t time, hence dc/dt going to 0 (c is constant) and the second derivative of dl/dt going to 0 as well (dl/dt constant). The end result is d$$^{2}$$b/dt$$^{2}$$ = (dl/dt)$$^{2}$$ - (db/dt)$$^{2}$$. a (acceleration) is the second deriv of b evidently. Can anyone tell me the reason behind differentiating twice, also how I could possibly use that formula in matlab? Thanks.

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