vest4R

thanks for your reply Alan. I was thinking that might be the case.

I see your image has been blocked. Would you be able to unblock it please?

In my opinion I don't think it matters if \(r = 0.83 + \frac{0.3}{1+0.3t}\) is substituted staight into p(t)

but I'm not overly confident about that.

thank you triggsy! just had a look at Partial Fraction Decomposition. Turns out they haven't taught us that yet.

thanks!

ultimately I have to solve it, but I should be right once it's in standard form.

I was thinking i'm being too picky and try to solve it with the separation methord. But I don't have an expression with t...

came up with another go for it...no idea if it's correct.

I'm confident i've got the correct ODE. (part a)

\(\frac{di}{dt} + \frac{1}{RC}i = \frac{d{V}_{s}}{dt}\frac{1}{R}\)

I come unstuck with part b

I'm not sure how to solve it with a \({V}_{s}(t) = 12t\)

If I use the non homogeneous methord to solve it,

I get a \({y}_{H} = i(t) ={C}_{1}{e}^{-\frac{1}{RC}t}\)

and then I don't know what my guess is for the RHS = \(\frac{d{V}_{s}}{dt}\frac{1}{R}\)

have I got the incorrect ODE in the first place?

any help is greatly appreciated!!

Thanks so much alan!

So I was making it much too complicated!

I just wanted to confirm with you, for question 4. once inputing the units m/s^2 for g,  k would = kg/s^2 ?

also as we're looking for the spring stiffness at each wheel, we're looking for k/4?

having trouble solving this, If anyone could even give me a tip to get started.

What I don't understand is,

Q1 how do you get the v^2 into an ode? how do I get rid of the square? If i derive it, I'll loose the drag coefficient d and thus can't solve Q2. If I was to then get v on it's own into an ODE. I'm not sure how to find d as i'll still have m as an unknown.

Q5 How do I find the spring stiffness k as I have the other unknowns of c and m.

Any help will be very greatly appreciated!

sorry, it just clicked..!! thanks for checking my post anyway!

Thank you!

Ended up getting there in the end, but wanted to keep the question up so I could get my answer confirmed.

Thanks for your help.