Question

http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s11_qp_11.pdf Question 35

Answer 1

@ameeron you there ?

Answer 2

Yes

Answer 3

Please help

Answer 4

firstly, this is math section and Q 35 belongs to engineering (or physics), so this is wrong place to post it, but since you are new here, i'll help you this time.
Do you know Current Division Rule ?

Answer 5

No, i don't

Answer 6

But i know that voltage is equal in a parallel circuit

Answer 7

read the resistive divider section first...
http://en.wikipedia.org/wiki/Current_divider

Answer 8

Yes yes, I know this rule

Answer 9

How can i use it here?

Answer 10

ok, so current in 1 ohm branch will be
I1 = 5 * (2||5) / (1+ 2||5)
got this ?

Answer 11

Not really, please explain further

Answer 12

the resistance of branch parallel to 1 ohm is the parallel combination of 2 ohm and 5 ohm
that makes RT in that formula.

Answer 13

What is RT?

Answer 14

\[what is this sign \left| ? \right| ?\]

Answer 15

||

Answer 16

|| means parallel

Answer 17

I know that the total resistance is equal to 10/7 , what should i do after that?

Answer 18

ok, lets go that way,
you know total, resistance, you know total current = 5A
then the voltage across them will be..... ?

Answer 19

Sorry, disconnection

Answer 20

we need to find the voltage across the 2 ohms resistor only?

Answer 21

voltage across each branch will be equal, as they are in parallel.

Answer 22

True

Answer 23

Then?

Answer 24

what voltage you got ?

Answer 25

10/7 multiply 5, right?

Answer 26

That will be 7.14V

Answer 27

now you have V across 2 ohm,
V= 7.14, R=2
find I using ohms law.

Answer 28

3.57A ?

Answer 29

That is none of the choices!

Answer 30

because i think 10/7 is incorrect.
R eq = (1/1 +1/2+1/5)^-1 = (17/10)^-1 = 10/17

Answer 31

and not 10/7

Answer 32

10/17*5/2 = 1.47 = 1.5 approx.

Answer 33

got it ?

Answer 34

Thanks alotttttttttt!!!! I had that silly mistake of taking 7 instead of 17!

Answer 35

you rock (:

Answer 36

and you please explain Question 9 too

Answer 37

can you*

Answer 38

please ask that in physics question, i am sure some1 will help you there...

Answer 39

No one wants to help!

Answer 40

i think that because the options are not correct ?
if the moving body sticks to stationary body, there will be no velocity and hence no K,E (K.E=0), but thats not a choice. Thats why even i was reluctant to answer that at first. But even i am not sure about this, i may be wrong...

Answer 41

When they say stick, they mean that they stick and move off together with the same velocity

Answer 42

oh, well..then i am not sure on how to find those....

Answer 43

Thank you anyways.. what's ur age btw?

Answer 44

Was just wondering

Answer 45

hmm.. i am 23

Answer 46

Engineer?

Answer 47

yes, completed graduation, and now pursuing post graduation.

Answer 48

if we are done with the question, can you please close the question ?
if you want to ask me anything else, message me.

Answer 49

Sure