GCSE physics question

[dave_s13]

My sis is doing a science equivalence course and is stumped with the following electricity questions.

I know about simple DC volts/amps/resistance stuff but not this.

Question described a motor in a circuit with a 3V battery

A. calculate the energy transferred to the motor when 10C of electrical charge passes through it

A resistor is now added to the circuit
When 10C of charge pass around this circuit, 8J of energy are dissipated in the resistor.

B. Find the p.d. across the resistor

c. find the energy transferred to the motor by the 10C of charge.



What the feck is a (C)????

Anyone care to answer the above with working outs???

[Demolisher 2]

C = Q = Couloumb = unit which charge is measured in = Current over time if I remember coorectly

HTH

Edited by Demolisher 2 on Wednesday 18th February 19:20

Edited by Demolisher 2 on Wednesday 18th February 19:20

[arryb]

C = Coulomb?

[cobra kid]

C is a Coulomb IIRC. The unit for electrical charge.

[SMKurt]

My guess.

[elster]

dave_s13 said:

My sis is doing a science equivalence course and is stumped with the following electricity questions.

I know about simple DC volts/amps/resistance stuff but not this.

Question described a motor in a circuit with a 3V battery

A. calculate the energy transferred to the motor when 10C of electrical charge passes through it

A resistor is now added to the circuit
When 10C of charge pass around this circuit, 8J of energy are dissipated in the resistor.

B. Find the p.d. across the resistor

c. find the energy transferred to the motor by the 10C of charge.



What the feck is a (C)????

Anyone care to answer the above with working outs???

If your sister is Kim, I just gave her the right answer.

[turbobloke]

Question described a motor in a circuit with a 3V battery

A. calculate the energy transferred to the motor when 10C of electrical charge passes through it

A resistor is now added to the circuit
When 10C of charge pass around this circuit, 8J of energy are dissipated in the resistor.

B. Find the p.d. across the resistor

c. find the energy transferred to the motor by the 10C of charge.

What the feck is a (C)????

Anyone care to answer the above with working outs???


In summary form:

A
1 volt = 1 joule (of energy E) per coulomb (that's the C)
or V = J/C (using the symbols)
so with V=3 and C=10 then E(nergy)= 30 joules i.e. 30J

B
do the same for R
so with C=10 and E(nergy)=8
then V(potential difference and voltage are being taken as the same)=0.8V

C
energy transferred 'to' the motor, if there's a p.d. drop of 0.8V across R
then there must be a 2.2V drop across the motor (0.8 + 2.2 =3)
so with V=2.2 and C=10 gives E(nergy)= 22 joules i.e. 22J

[dave_s13]

elster said:

dave_s13 said:

My sis is doing a science equivalence course and is stumped with the following electricity questions.

I know about simple DC volts/amps/resistance stuff but not this.

Question described a motor in a circuit with a 3V battery

A. calculate the energy transferred to the motor when 10C of electrical charge passes through it

A resistor is now added to the circuit
When 10C of charge pass around this circuit, 8J of energy are dissipated in the resistor.

B. Find the p.d. across the resistor

c. find the energy transferred to the motor by the 10C of charge.



What the feck is a (C)????

Anyone care to answer the above with working outs???

If your sister is Kim, I just gave her the right answer.

Yes she is!!!

Fvck me, it's a small world

[elster]

dave_s13 said:

Yes she is!!!

Fvck me, it's a small world

It is indeed.

[dave_s13]

turbobloke said:

Question described a motor in a circuit with a 3V battery

A. calculate the energy transferred to the motor when 10C of electrical charge passes through it

A resistor is now added to the circuit
When 10C of charge pass around this circuit, 8J of energy are dissipated in the resistor.

B. Find the p.d. across the resistor

c. find the energy transferred to the motor by the 10C of charge.

What the feck is a (C)????

Anyone care to answer the above with working outs???


In summary form:

A
1 volt = 1 joule (of energy E) per coulomb (that's the C)
or V = J/C (using the symbols)
so with V=3 and C=10 then E(nergy)= 30 joules i.e. 30J

B
do the same for R
so with C=10 and E(nergy)=8
then V(potential difference and voltage are being taken as the same)=0.8V

C
energy transferred 'to' the motor, if there's a p.d. drop of 0.8V across R
then there must be a 2.2V drop across the motor (0.8 + 2.2 =3)
so with V=2.2 and C=10 gives E(nergy)= 22 joules i.e. 22J

Nice one, I actually got it right, to my surprise!

The coulumb thing threw me a bit.

[dave_s13]

elster said:

dave_s13 said:

Yes she is!!!

Fvck me, it's a small world

It is indeed.

She'd do well to learn how to fvckin google it and post on places like this....it'd save me the bother.

[elster]

dave_s13 said:

elster said:

dave_s13 said:

Yes she is!!!

Fvck me, it's a small world

It is indeed.

She'd do well to learn how to fvckin google it and post on places like this....it'd save me the bother.

Tell her to stop being so lazy. She never said she had a normal brother who was a car geek like myself.

[AlpineWhite]

Now we've got that sorted, does anyone know what would happen if you put a plan on a conveyor belt?

[TheEnd]

AlpineWhite said:

Now we've got that sorted, does anyone know what would happen if you put a plan on a conveyor belt?

it'd move to the far end, and be "subducted" into the mechanism?

[elster]

AlpineWhite said:

Now we've got that sorted, does anyone know what would happen if you put a plan on a conveyor belt?

I have installed a conveyor belt. At one point the plans were indeed on the conveyor belt. The result was the plans moved as the belt moved.

[AlpineWhite]

There's a headwind too.


Obviously.

Edited by AlpineWhite on Wednesday 18th February 19:58

[dave_s13]

elster said:

dave_s13 said:

elster said:

dave_s13 said:

Yes she is!!!

Fvck me, it's a small world

It is indeed.

She'd do well to learn how to fvckin google it and post on places like this....it'd save me the bother.

Tell her to stop being so lazy. She never said she had a normal brother who was a car geek like myself.

She's got 2! Other brother has an rx8.

She is feckless sometimes but i do hope the latest becoming a teacher venture comes to fruition. Thanks for the coulumb tip, very surreal post this one :-)

Edited by dave_s13 on Wednesday 18th February 20:00

[s3fella]

Surely, if it's GCSE, there is a 25% chance of getting it right, A, B C or D, using the Homer J Simpsopn "Mo" method...!

[elster]

dave_s13 said:

elster said:

dave_s13 said:

elster said:

dave_s13 said:

Yes she is!!!

Fvck me, it's a small world

It is indeed.

She'd do well to learn how to fvckin google it and post on places like this....it'd save me the bother.

Tell her to stop being so lazy. She never said she had a normal brother who was a car geek like myself.

She's got 2! Other brother has an rx8.

She is feckless sometimes but i do hope the latest becoming a teacher venture comes to fruition. Thanks for the coulumb tip, very surreal post this one :-)

Edited by dave_s13 on Wednesday 18th February 20:00

I did double take when I saw this post after the texts.

I do believe I am teaching her about Ohms Law on MSN tomorrow. She gets annoyed as I don't give her the answers but try to teach her.

Hope she does get her science sorted, so she can be a teacher. God knows why anyone would want to deal with kids though!

Edited by elster on Wednesday 18th February 20:12