UNIT 7: calculus to solve engineering problems

The same capacitor circuit is now charged up to 12V and the instantaneous voltage is v=12(1- e^-t/2)a) Differentiate v with respect to t to give an equation for dv/dt?

Reply 1

Filthy Communist

12

Chain rule.

d/dt(12) = 0 so you only have to worry about d/dt(-12e^(-t/2))

To rigorously explain it, I'd substitute u = -t/2 and apply the chain rule, but I can't be bothered so I'll just tell you that the derivative of e^f(x) = f'(x)e^f(x), so the derivative of -12e^(-t/2) is just 6e^(-t/2).

(edited 2 years ago)

Reply 2

18butterfly

1

Hi i was just wodnering what grade you got on unit 7 and 8 coursework. Also i you got a distinction do you still have your answers. If yes would you be able to give them to me as i am struggling really bad with this assignment and i need a distinction to get into university.

Reply 3

18butterfly

1

Original post by Filthy Communist

Chain rule.

d/dt(12) = 0 so you only have to worry about d/dt(-12e^(-t/2))

To rigorously explain it, I'd substitute u = -t/2 and apply the chain rule, but I can't be bothered so I'll just tell you that the derivative of e^f(x) = f'(x)e^f(x), so the derivative of -12e^(-t/2) is just 6e^(-t/2).

Hi i was just wodnering what grade you got on unit 7 and 8 coursework. Also i you got a distinction do you still have your answers. If yes would you be able to give them to me as i am struggling really bad with this assignment and i need a distinction to get into university.

Reply 4

davros

16

Original post by 18butterfly

Hi i was just wodnering what grade you got on unit 7 and 8 coursework. Also i you got a distinction do you still have your answers. If yes would you be able to give them to me as i am struggling really bad with this assignment and i need a distinction to get into university.