Question about Capacitance and Inductance

[Mohamed Abdul]

Homework Statement

[/B]
Hey everyone, I recently got two problems on capacitance and inductance and need some help on them. Here are the two problems:

1. A Royal Red Robin Burger contains 1230 food calories. Also, more that the daily requirement for protein, fat, sodium ..., even without fries or a drink. Convert this number of calories to Joules. For the amount of energy you have calculated, determine the voltage V (in kVolts) on a capacitor C = 1.1 Farads.

2. A capacitor C = 33 micro-Farads is charged up to a voltage V = 16.1 Volts. It is then connected to an inductor L = 65 milli-Henries using a switch. The energy will oscillate back and forth between the capacitor and inductor. When all of the energy is in the inductor, what current I will it be carrying? Express your answer in milli-Amps.

Homework Equations

E = .5CV^2 I=sqrt(2E/L)

The Attempt at a Solution

For the first question, I multiplied 1230 by 4.18, and set that number (5141.4) equal to .5(1.1)(V^2). Then I solved for V and got /0967 kVolts.

For the second one I multiplied .5*.000033 farads*16.1^2 and got .03888 Joules. Then I set that equal to the second equation and substituted E and L and got 345.88 milliamps.

I want to know if I'm on the right track for this problem, since this is my final allowed attempt at it.

 

[rude man]

For the first question, I multiplied 1230 by 418

418 ??

For the second one I multiplied .5*.000033 farads*16.1^2 and got .03888 Joules.

I got 4.28e-3 joules.

 

[Mohamed Abdul]

418 ?? Better check that second equation ...

Is that not the equation for current. If so, then what is? Also I got the 418 because there are 4.18 joules per calorie and I forgot the decimal, sorry,

 

[Mohamed Abdul]

I got 4.28e-3 joules.

I redid my math and got that as well, my final answer for question 2 is now 362.766 amps. Did that line up with what you got?

 

[rude man]

Is that not the equation for current. If so, then what is? Also I got the 418 because there are 4.18 joules per calorie and I forgot the decimal, sorry,

I thought I edited that cooment out. Your eq. is correct, the math was not.

 

[rude man]

I redid my math and got that as well, my final answer for question 2 is now 362.766 amps. Did that line up with what you got?

Exactly.

 

[Mohamed Abdul]

I'm still wondering if I did the right steps on the first problem, as I've constantly been making errors on those types of questions. I'm not sure if its due to a rounding mistake or a genuine error.

 

[rude man]

I'm still wondering if I did the right steps on the first problem, as I've constantly been making errors on those types of questions. I'm not sure if its due to a rounding mistake or a genuine error.

You still did not do the calories to joules conversion correctly.
Fact: 1 food calorie = 1000 cgs calories. 1 food calorie = 4.18 kilojoules, not joules.