Physics Paper 2 help needed

[AE-12]

Physics Paper 2 June 2008 question 6...please explain

 

[beacon_of_light]

ive explained that before in another topic...

 

[AE-12]

can u please copy it here thanks

 

[beacon_of_light]

may 08 Q6 b...

Just remember one rule, the current ''likes'' to flow through the path with lowest resistance. here in this diagram, if switch S2 would be closed, current will flow through switch S2 but not through resistance B.

row1: power is zero since no current flows through circuit.

row2:now total resistance will be 38.4 ohms only coz current will not flow through resistance B as an alternative low resistance path by S2 is provided.

power is v^2/R .....(240)^2/ 38.4 ...power is 1.5 ohms.

Solve out other rows in the same way...

 

[AE-12]

thanks...u shud be a techer ;D

 

[AE-12]

hey could also explain S09 variant 1 Q7 part (a) and N09 QP22 Q1 part (c)

 

[beacon_of_light]

hey could also explain S09 variant 1 Q7 part (a) and N09 QP22 Q1 part (c)

BAD IDEA of being a TEACHER!!! :?

q7(a): there's only R b/w A and C! you don't need to consider the other open end!

FOR B and X, consider BCXY...so two resistances in parallel...total resistance would be 0.5R

FOR A and Z, consider the whole circuit! R+R+0.5R = 2.5R ......

Nov09 : uncertanity in the value of g is 4.2% or +- 0.4....now how come the answer is written to 4 sig.figures....when the uncertainity is to two sig.fig..answer needs to be to 2 sig,,fig,,,or just see the data of T and L..its maximum to 3 sig.figures...so you need to write the answer in the same form!!!

 

[AE-12]

how come the uncertainity is +-0.4??

 

[beacon_of_light]

4.2/100 x 9.81 = 0.4