# Search results

1. ### Charging a capacitor

Cheers, too late now, missed my deadline. I can't believe all I needed was the product rule (what I'm currently doing in maths .. oh man). I'll play with this later in the week when I have a little free time. Thanks for the help.
2. ### Charging a capacitor

One last request for help. I have an hour and a half until I need to submit this.
3. ### The formulas for parallel and series connections

Here's my thinking, the two x 4s are essentially a single 2. So from that side it can go along either 2 ohm path. Then they'd cancel each other out going through the 5, so no current flows through that resistor.
4. ### The formulas for parallel and series connections

I'd be thinking something like this : And keep simplifying parallel circuits til things look simpler. Again, warning, not my specialty, but something to think about. You seem to have an answer, see if you can keep reducing it in that fashion and see what you get.
5. ### The formulas for parallel and series connections

Most of the current will take the easiest path, but that doesn't mean it all does. Eg, Circuit has branch, one has 2ohm resistor, the other 4. Do you really think it ALL goes via the easier path? Picture a supermarket queue. There's a fast moving 10 items or less queue, or a slow moving...
6. ### The formulas for parallel and series connections

Looking at the original diagram, current can go through the first 4's then come back through the 5, This isn't possible on your diagram. (also it could then go through the 20 from the 5 - again, not possible on your diagram). Not sure what the question is asking but I'd start simplifying...
7. ### Charging a capacitor

Is (b) requiring me to use ω CV Sin(ωt + pi/2) ??? Aside from that, I'm out of ideas. Anyone ??
8. ### Charging a capacitor

Cheers, you're right, its 9.55 x 10^-7, so 0.955 uA. Any hints for b and d ??
9. ### Charging a capacitor

For (C) I'm assuming its P=I^2 R = 9.55x10^-6 * 3000000 = 2.74 x 10^-6 Watts ??
10. ### Charging a capacitor

Nothing I can find. Can't even google myself a formula. Closest guess would be - But I'm not even sure what dq are in this?
11. ### Charging a capacitor

Is (b) just 1/2 QV, so 1/2 * 1/4 = 2 somethings ? And (d) just QV, so 1x4 = 4.
12. ### Charging a capacitor

Just realised it only wants the rate, and not the rate of change of these things. So (a) we are looking for current, so E/R e^(-t/RC) = 4/3000000 * e^(-1/3) = 9.55uA ?? (b) energy I guess I use U = 1/2 CV^2 ? (c) Relates to Power, so P=I^2*R (d) can wait.
13. ### Charging a capacitor

Homework Statement A 3.00 MΩ resistor and a 1.00 μF capacitor are connected in series with an ideal battery of emf E = 4.00 V. At 1.00 sec after the connection is made, what is the rate at which (a) the charge of the capacitor is increasing; (b) energy is being stored in the capacitor; (c)...
14. ### Circuits .. what is this question asking?

Thanks heaps. Feeling stupid. Not good when I'm stuck on one of the first questions. Appreciate the quick response. Now I can enjoy my wine in peace.
15. ### Circuits .. what is this question asking?

That makes sense. I assume I'm okay on the other two?
16. ### Circuits .. what is this question asking?

Cheers. Ok, in that case its when the current through the circuit is zero, so basically when we have a switch or a resistor with infinite resistance?
17. ### Circuits .. what is this question asking?

Homework Statement A battery has an emf E and internal resistance r. A variable resistor R is connected across the terminals of the battery. Find the values of R such that (a) the potential difference across the terminals is a maximum; (b) the current in the circuit is a maximum; (c) the power...
18. ### Calculating Gravity from Inclined plane

here's the solution they provided - https://youtu.be/IED3ujslfPY. I got a slightly different answer because I calculated acceleration differently. I used values associated with t^2 and ran least squares on them to get my value for the slope, he used √d values - i thought they'd give same answer...
19. ### Calculating Gravity from Inclined plane

Once again, thanks for your help and patience. Will let you know if we got the answer my teacher expected.
20. ### Calculating Gravity from Inclined plane

1/[x^2 / (x^2 + 2/5 r^2)] * a * sinθ so 1/[10.41^2 / (10.41^2 + 2/5 * 15^2) * 0.1646 * (0.061/2)] = 9.866 Answer looks good,how'd I go with this one?
21. ### Calculating Gravity from Inclined plane

Which means our ratio should be 1 / (2/5 r^2/x^2 + 1) ??
22. ### Calculating Gravity from Inclined plane

KE=1/2Iω^2 KE=1/2I(v^2/x^2) ??
23. ### Calculating Gravity from Inclined plane

K_linear = 1/2mv^2 K_rotational = 2/5mr^2 + mx^2 ? Total KE = 1/2mv^2 + 2/5mr^2 + mx^2 ?? So rotional/linear = (1/2 v^2) / (2/5r^2 + x^2) ?? ???
24. ### Calculating Gravity from Inclined plane

What are we working towards here, total Kinetic energy ? Sorry, it's just not clicking. What's our end goal here? If I know what we're working towards that might help me put the pieces into place. We have a value for x, are we trying to work out ω, or looking for something to substite in place...
25. ### Calculating Gravity from Inclined plane

ω So just v=xω then
26. ### Calculating Gravity from Inclined plane

v= (r-x)ω ???
27. ### Calculating Gravity from Inclined plane

I_com=2/5mr^2 ? So I = 2/5mr^2 + mx^2 ?
28. ### Calculating Gravity from Inclined plane

v= rω ?? Moment about the axis? No idea. I_com + Mr^2 ? Honestly, what am I missing? Can you maybe explain this like I'm 5? I can't find anything discussing these ideas that dont include mass, and I can't see how to remove the mass from the equation, and I can't see how we calculate the inertia...
29. ### Calculating Gravity from Inclined plane

Appreciate the assistance. But I've already spent WAY too long on this problem. It's only worth a single bonus mark. It's not worth my mental heath to continue it further. I'll just wait for the answer and live without that mark. Thanks for the help though.
30. ### Calculating Gravity from Inclined plane

Avoid plugging numbers in? I dont even know what formula i'm supposed to be using. I have no idea what you're talking about. Sorry, but I give up. I'm going to need something beyond these cryptic clues. This is my first month of physics and this is all well above my head.