ALL CIE PHYSICS DOUBTS HERE !!!

[Deadly_king]

Yeah, I knew that. Thanks guys.

+rep to both of you.

Anytime buddy

[$H00t!N& $t@r]

Question!

Find the diameter of a copper wire which has the same resistance as an aluminium wire of equal length and diameter 1.20 mm. The resistivities of copper and aluminium at room temperature are 1.7 x 10^-8 ohm metres and 2.6 x 10^-8 ohm metres respectively.


The answer is 0.97 mm

[Katatonia]

R= rhoL/ A

Find R for aluminium. l is constant, so don't bother. rho is resistivity.

R= 2.6x10^-8/ pi X 0.6^2

R= 2.3X10^-8

So diameter of copper wire for same Resistance is given by

2.3X10^-8= 1.7x10^-8/ pi X r^2

r=0.485mm
d=0.97 mm (2r)

[elemis]

+rep Katatonia.

Glad to see you finally posting around

[elemis]

Question 15

How do we determine the answer ?

I've tried arranging them all in vector triangles, yet all of the lines are apparently in sequence and hence all systems are in equilibrium.

How do you do questions like these ?

[ashish]

Question 15

How do we determine the answer ?

I've tried arranging them all in vector triangles, yet all of the lines are apparently in sequence and hence all systems are in equilibrium.

How do you do questions like these ?

according to me C and D cancels out because the length of one force in one direction is too big
and the answer is for sure A
i try to resolved the two perpendicular forces and the length is equal to the diagonal force

hope it helps

[elemis]

Question 7  CLICK HERE

What is the answer and why ?

[blackberry]

the answer is supposed to D but i dont really know how!! 

[elemis]

No, I dont understand.

How is it that the acceleration at T = Q

[ashish]

No, I dont understand.

How is it that the acceleration at T = Q

there was something wrong in my last post(i removed it )

here is the way to get the answer

at T there is only gravitational force which acts on the body as the body has stop decelerating (v=0)
after point T only gravitational force act on the body thus Accn at T should be equal to accn at Q

[elemis]

there was something wrong in my last post(i removed it )

here is the way to get the answer

at T there is only gravitational force which acts on the body as the body has stop decelerating (v=0)
after point T only gravitational force act on the body thus Accn at T should be equal to accn at Q

Yeah, I think I've got it.

Thanks man +rep

[elemis]

Part (a) whats the direction ?

[Deadly_king]

Part (a) whats the direction ?

It's got to be vertically upwards since it is a torque.

The torques of a couple only results when the two forces are parallel to each other.

[elemis]

http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w01_qp_2.pdf

3 (c)(iii)

Whats the direction ? I'd appreciate a diagram, as that would make things clearer.

[Deadly_king]

http://www.xtremepapers.net/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w01_qp_2.pdf

3 (c)(iii)

Whats the direction ? I'd appreciate a diagram, as that would make things clearer.

According to me, the direction should be from the hinge along the lid.

Try here, it might clear your doubts.

AM sorry but I can't provide for diagrams.