# Trying to solve for derivative with respect to time of vector given magnitude and two angles [closed]

I've got a problem involving dynamic vectors in which I'm being asked to find $$\dot R$$ $$\dot \theta_a$$ and $$\dot \theta_e$$

I'm given the vector of $$(R,\theta_a,\theta_e)$$ = $$(25,-120,15)$$ and $$V_{cm} = 200\hat{i} - 300\hat{j} - 100\hat{k}$$

turned the spherical coordinates into cartesian for $$R_{cm} = -5.60\hat i - 20.91\hat j - 24.14\hat k$$

The magnitude $$V = 374.16$$ with the angles $$= -56.03$$ and $$-15.5$$ in respect to the horizontal and vertical planes.

The issue I'm having is find $$\dot R$$ $$\dot \theta_a$$ and $$\dot \theta_e$$ which also known as $$\frac{dR}{dt}, \frac{d\theta_a}{dt}, and \frac{d\theta_e}{dt}$$

What I'm running into which is causing my problem is I don't see any actual variables to do any derivation to get anything other than $$\dot R = 0$$, $$\dot \theta_a = 0$$ and $$\dot \theta_e = 0$$

How would one do implicit derivation for this situation?

• Frp spherical polar coordinate, your natations are very different. from the usuaul $(r, \theta, \phi)$. What is your $\theta_a$ and $\theta_e$? – ytlu Feb 7 at 15:53
• This problem does not make sense: you can not derive simply derive a vector if you don't know what and how is changing with time. You have to write your trasnformations in symbols (R, $\theta_e$, etc.), decide what depends on time (R(t)? $\theta_e(t)$?) and then carry out the derivatives (there will be composite products so you need the chain rule etc.). But then you need to know the function $R(t)$ or $\theta_e(t)$ to solve it completely.. – JalfredP Feb 7 at 16:32