Physics: Post your doubts here!

[Suchal Riaz]

Y u used in part ii) IV and in part iii) I^2R ?

V=IR
in P = IV use (v=ir)
P=I(IR)=I²R

 

[Thought blocker]

V=IR
in P = IV use (v=ir)
P=I(IR)=I²R

Still din't get you, y we dont use P=V^2/R in part ii) or P = IR in part iii) ?

 

[Suchal Riaz]

Still din't get you, y we dont use P=V^2/R in part ii) or P = IR in part iii) ?

we can use any of them as long as we use correct value or R, V and I
i used the one with I and V because the generator's emf and I already given.
and in other part i used the one with I because if i used V when i would have to find the p.d across resistors. if we used P=V²/R = 8²/4=16. same answer.

 

[Thought blocker]

we can use any of them as long as we use correct value or R, V and I
i used the one with I and V because the generator's emf and I already given.
and in other part i used the one with I because if i used V when i would have to find the p.d across resistors. if we used P=V²/R = 8²/4=16. same answer.

ty

 

[Zepudee]

We use P=VI to determine the efficiency? and how do we use it? Can give some examples? Thanks a lot!!

 

[Thought blocker]

We use P=VI to determine the efficiency? and how do we use it? Can give some examples? Thanks a lot!!

Use efficiency formula, (Input power / output power) * 100

 

[Suchal Riaz]

We use P=VI to determine the efficiency? and how do we use it? Can give some examples? Thanks a lot!!

in this question we first found total power, then wasted power and then efficiency.

 

[EddieX]

Aoa,
Guys if anyone of u have COMPLETE PHYSICS DEFINATIONS FOR AS Level ... Please share!
As well as the best and detailed explanation for projectile motion ... Would be well appreciated
URGENT HELP PLEASE!
Thank you

hope this helps mate i found a while back

 

[DeViL gURl B)]

hope this helps mate i found a while back

Thank you soooo MUCH!!
Just wanted to ask .... If u've any other useful notes as well..cuz these seem quite useful thank u
Please share.. If u do

 

[Thought blocker]

Thank you soooo MUCH!!
Just wanted to ask .... If u've any other useful notes as well..cuz these seem quite useful thank u
Please share.. If u do

This might help u more

 

[Princess Raven]

Guys can someone show me how to draw a speed time and velocity time graph for throwing a ball upwards

 

[Thought blocker]

Guys can someone show me how to draw a speed time and velocity time graph for throwing a ball upwards

http://www.examsolutions.net/maths-revision/mechanics/kinematics/velocity-time-graphs/tutorial-1.php

 

[Faithix MFSH]

Can someone please help me with this one?


I know how these questions go but this one seems abit tricky.

They said
A graph is plotted of V/E on the y-axis against 1/R on the x-axis. Express the gradient in terms of F.

Now if the gradient is y/x I get
Gradient = VR/E

Now in terms of F
From the equation, F = VR/E - R
So gradient is F+R

Now R = FE/(V-E)
So if we replace that too in our F+R gradient equation we dont end up with F.

Thats the answer in the ms, F. Gradient = F.

Can someone please solve this and if went right, explain it to me kindly?

Highly appreciate it.

 

[DeViL gURl B)]

This might help u more

Thank u
But isn't this for A2 as in all I need is AS ...

 

[Thought blocker]

Thank u
But isn't this for A2 as in all I need is AS ...

Both are combined, and easy.

 

[DeViL gURl B)]

Both are combined, and easy.

Okha.. Thank u
But actually I was thinkin of being specific .. I mean who wants to read extra stuff
But thank a lot !

 

[GlitteringLights]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w07_qp_4.pdf

hi i have a doubt in this paper, ques # 1 (b)(ii)
this is the answer the ms provides :

"force in cord = weight + centripetal force (can be an equation) ..........................C1
force in cord = (L – 13) × 5/1.8 or force constant = 5.0/1.8 ................................C1
(L – 13) × 5/1.8 = 5.0 + 5/9.8 × L × 10^-2 × 8.7^2
..................................................C1
L = 17.2 cm ...........................................................................................................A1 [4]
(constant centripetal force of 5.0 N gives L = 16.6 cm allow 2/4) "

can someone please clarify whether f=mv^2 /r [centripetal force right?] is being used and why is the 'r' is being multiplied instead of divided? (radius r is Lx10^-2)

 

[Someone2]

Can someone please help me with this one?


I know how these questions go but this one seems abit tricky.

They said
A graph is plotted of V/E on the y-axis against 1/R on the x-axis. Express the gradient in terms of F.

Now if the gradient is y/x I get
Gradient = VR/E

Now in terms of F
From the equation, F = VR/E - R
So gradient is F+R

Now R = FE/(V-E)
So if we replace that too in our F+R gradient equation we dont end up with F.

Thats the answer in the ms, F. Gradient = F.

Can someone please solve this and if went right, explain it to me kindly?

Highly appreciate it.

V=FE/R + E
V=E{F/R + 1}
V/E=F/R + 1 where V/E is y and 1/R is x in the form y=mx+c

hope u get it

 

[EddieX]

Thank you soooo MUCH!!
Just wanted to ask .... If u've any other useful notes as well..cuz these seem quite useful thank u
Please share.. If u do

You are most welcome. Here these are all i have

 

[EddieX]

the rest