Physics: Post your doubts here!

[AlishaK]

I kinda wanna confirm something. Why does the gravitational potential has a neg sign in it's formula?!
xhizors
Jazak Allah khair.

 

[snowbrood]

I kinda wanna confirm something. Why does the gravitational potential has a neg sign in it's formula?!
xhizors
Jazak Allah khair.

aslamalaikum
look u have to consider velocity of body going up as poisitve and body going down as negative.
case 1.
when u throw a ball upwards its speed decreases to zero so u would conclude that there is deceleration which means negative accleration .
case 2
when the ball from that highest point reached now goes downward u might consider as acceleration positive one but no its wrong.
velocity will increase but it will be negative so again negative acceleration.
now u would conclude that g is always negative

 

[AlishaK]

aslamalaikum
look u have to consider velocity of body going up as poisitve and body going down as negative.
case 1.
when u throw a ball upwards its speed decreases to zero so u would conclude that there is deceleration which means negative accleration .
case 2
when the ball from that highest point reached now goes downward u might consider as acceleration positive one but no its wrong.
velocity will increase but it will be negative so again negative acceleration.
now u would conclude that g is always negative

Wsalaam, Thanks, but i never mentioned a neg sign for a body falling towards the earth?! as per ur example a Ball. :/isn't it that gravity acts downward so it'll b positive?!

 

[snowbrood]

Wsalaam, Thanks, but i never mentioned a neg sign for a body falling towards the earth?! as per ur example a Ball. :/isn't it that gravity acts downward so it'll b positive?!

a=v-u/t and as V final velocity will always be negative for a body moving downwards so the acceleration will be negative.. in alevels u do have to give positive and negative signs its not o levels

 

[snowbrood]

a=v-u/t and as V final velocity will always be negative for a body moving downwards so the acceleration will be negative.. in alevels u do have to give positive and negative signs its not o levels

u know that final velocity will be greater than u and it will be negative so acceleration will also be negative

 

[AlishaK]

u know that final velocity will be greater than u and it will be negative so acceleration will also be negative

So, u mean when for eg: the ball is thrown up, the neg sign is 'cause of the deceleration and when it falls down, the neg is 'cause of the velocity (as we took it negative for downward)

Thanks a lot. :')
Stay blessed

 

[Alevel Romeo]

someone gave me a link chemguide.co.uk and it helped in chemistry a lot! and i did a B grade performance in p4 chemistry and same condition here !
i want to prepare physics and 24 hours left for it's p4 and i have not attended any classes and i dont have any notes! notes posted here are not of the updated syllabus!
i have a physics a level book and i could not filer out materials so is here anyone who can help me? i had B (77) in AS physics and i want to score a good marks in A2 so that i can score A in total!
please help me and provide me notes of just A2 and we all can have a good exam!

 

[SararaIH]

Tomorrow's the exam and I'm freaking out because I didn't have much time to study
And right now I just have the whole day left today
I feel like I've forgotten everything of physics! :'(
Please anybody kindly tell me what to do and how I can revise everything quickly! PLEASE!

 

[Soldier313]

Q9b(i) graph part ms says square graph.. ?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_42.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_ms_42.pdf

I believe it's a graph with a square wave form due to saturation, so when V2 is greater than V1 it's positive saturation, and when V1 is greater than V2 it's negative saturation. Hence resulting in a graph with a square wave form.
Hope that helped.

 

[nishan2052]

plz someone explain use of base station at both ideal and active time of cell phones?

none replied.........

 

[Alevel Romeo]

what is root mean square value can anyone please describe?

 

[Alevel Romeo]

what is root mean square value can anyone please describe?

 

[kelly sheers]

what is root mean square value can anyone please describe?

RMS (root mean square) voltage is the equivalent DC voltage that produces the same power dissipation in a load (heating effect in a resistor) or the same power transfer in a conductor. R,M,S voltage is the AC voltage

 

[xhizors]

I believe it's a graph with a square wave form due to saturation, so when V2 is greater than V1 it's positive saturation, and when V1 is greater than V2 it's negative saturation. Hence resulting in a graph with a square wave form.
Hope that helped.

and what about the starting point!!

 

[SararaIH]

Can anyone suggest which question papers I should practice for the last couple of hours that I've got?

 

[xhizors]

I kinda wanna confirm something. Why does the gravitational potential has a neg sign in it's formula?!
xhizors
Jazak Allah khair.

b/c work gets out whenever works gets out we place a -ve sign !

 

[Soldier313]

and what about the starting point!!

This is what i think it has to look like. It's not exactly neat, but i hope it gives you an idea!

 

[AlishaK]

b/c work gets out whenever works gets out we place a -ve sign !

thanks. :')

 

[SararaIH]

Can anyone suggest which question papers I should practice for the last couple of hours that I've got?

 

[AlishaK]

Can anyone suggest which question papers I should practice for the last couple of hours that I've got?

M/j 2012, O/N 2012, Mj/ON 2011.