Physics: Post your doubts here!

[anastasia grey113]

Surprising...this doesn't appear on our statements

well u must be a pakistani candidate then
it used to show up until in 2010, there was some issue with equivalence n all...long story
so they stopped sending PUMS here.

 

[A*****]

well u must be a pakistani candidate then
it used to show up until in 2010, there was some issue with equivalence n all...long story
so they stopped sending PUMS here.

That's bad

 

[anastasia grey113]

That's bad

yh
it was like...a student who got a 65/100 in Islamiat was given an A* according to threshold but the PUMS was written as 60% so the IBCC was accepting the PUMS instead of the grade (in this case, the 60% was considered for equivalence, not the 90% for A* as its done now) This put the CIE students at a disadvantage.
So the IBCC stopped CIE to send PUMS from then on and alotted marks to each grad by themselves e.g 90 for A*, 85 for A and so on.

 

[A*****]

yh
it was like...a student who got a 65/100 in Islamiat was given an A* according to threshold but the PUMS was written as 60% so the IBCC was accepting the PUMS instead of the grade (in this case, the 60% was considered for equivalence, not the 90% for A* as its done now) This put the CIE students at a disadvantage.
So the IBCC stopped CIE to send PUMS from then on and alotted marks to each grad by themselves e.g 90 for A*, 85 for A and so on.

Ohh right!

 

[Mijandi@7]

Need some help over here

A small diesel engine uses a volume of 1.5 × 104 cm3
of fuel per hour to produce a useful power
output of 40kW. It may be assumed that 34 kJ of energy is transferred to the engine when it uses
1.0 cm3
of fuel.
What is the rate of transfer from the engine of energy that is wasted?
A 102 kW B 142 kW C 182 kW D 470 kW

Don't understand how to get the Answer which is A. Help is appreciated thanks

 

[anastasia grey113]

Need some help over here

A small diesel engine uses a volume of 1.5 × 104 cm3
of fuel per hour to produce a useful power
output of 40kW. It may be assumed that 34 kJ of energy is transferred to the engine when it uses
1.0 cm3
of fuel.
What is the rate of transfer from the engine of energy that is wasted?
A 102 kW B 142 kW C 182 kW D 470 kW

Don't understand how to get the Answer which is A. Help is appreciated thanks

Since we are talking in terms of power which is energy per second, we should be doing all our calculations of energy for 1 second only.

Well the volume is 1.5 x 10^4 per hour so per second the volume consumed should be
1.5 x 10^4/3600 = 4.17 cm3 <------ this is the volume consumed per second.

Now the energy transferred per second will be
4.17 x 34 = 141.7 kJ <----- it can be called the power transferred to the engine as well becuz its energy per second right?

Moving on to the power wasted.
Now the 141.7kJ is the TOTAL power.
While 40kJ is the useful power.
So to find the waste --------> total - useful = 141.7 - 40 = 101.7
Round it off to 102 kJ
Hoping it helped

 

[Mijandi@7]

Since we are talking in terms of power which is energy per second, we should be doing all our calculations of energy for 1 second only.

Well the volume is 1.5 x 10^4 per hour so per second the volume consumed should be
1.5 x 10^4/3600 = 4.17 cm3 <------ this is the volume consumed per second.

Now the energy transferred per second will be
4.17 x 34 = 141.7 kJ <----- it can be called the power transferred to the engine as well becuz its energy per second right?

Moving on to the power wasted.
Now the 141.7kJ is the TOTAL power.
While 40kJ is the useful power.
So to find the waste --------> total - useful = 141.7 - 40 = 101.7
Round it off to 102 kJ
Hoping it helped

thanks for solving

 

[Anirudh Singh]

Where can i get answers of physics, chemistry, bio textbook exercises

 

[Anirudh Singh]

where can i get the answers of textbook exercise of phy, chemistry and bio

 

[Anirudh Singh]

where can i get the answers of textbook exercise of phy, chemistry and bio

 

[Anirudh Singh]

where can i get the answers of textbook exercise of phy, chemistry and bio

 

[Anirudh Singh]

where can i get the answers of textbook exercise of phy, chemistry and bio

 

[Anirudh Singh]

where can i get the answers of textbook exercise of phy, chemistry and bio IGCSE

 

[studyingrobot457]

W

where can i get the answers of textbook exercise of phy, chemistry and bio IGCSE

Why so much spamming, you get them on the CD, you can get CD files from gceguide.xyz

 

[Saikat Alam]

Can someone explain Kirchhoff's laws to derive the resistance formulae?

 

[Kanekii]

Can someone explain Kirchhoff's laws to derive the resistance formulae?

Kirchoffs first law states that the amount of current flowing in a junction is equal to the amount leaving junction so therefore:
I=I1 +I2
V/Rt=V/R1 + V/R2
Cancel V
1/Rt=1/R1 + 1/R2
Keep in mind this is only for parralel circuits

 

[Kanekii]

I would advise you to give them in may as composite because you know A2 is also difficult and if you keep on preparing for A1 till oct than you will have very little time left for A2 which will be a disadvantage.
A2 syllabus includes all that learned in A1 and A2 thus it will also help you revise for your paper 4 & 5.
Stay calm ...stay focused and work hard for the next 6 months and please try and stay away from every leisure activity.
This is a very precious time don't waste it.
Inshallah you will be successful.Work hard and leave the rest to Allah.

InshaAllah,you too
Thanks alot I feel alot better now, i've thoroughly planned my counter strategy . Since i had 4 subjects i'll drop one subject which is Bio since my passion is in computer science engineering. I'll give Excel for Chem and Maths only and i'll carry my Physics grade

 

[Hamnah Zahoor]

InshaAllah,you too
Thanks alot I feel alot better now, i've thoroughly planned my counter strategy . Since i had 4 subjects i'll drop one subject which is Bio since my passion is in computer science engineering. I'll give Excel for Chem and Maths only and i'll carry my Physics grade

You are welcome... Inshallah you will be successful next time.

 

[A*****]

InshaAllah,you too
Thanks alot I feel alot better now, i've thoroughly planned my counter strategy . Since i had 4 subjects i'll drop one subject which is Bio since my passion is in computer science engineering. I'll give Excel for Chem and Maths only and i'll carry my Physics grade

Good decision to drop bio...A2 bio is ridiculous!
Btw from where are u planning to do cs engineering?

 

[Kanekii]

Need help with this:
A simple pendulum suspended from a fixed point, Consists of a light cord of length 500mm and a bob of weight 2N. The bob is made to move in a horizontal circular path. If the maximum tension which the cord can withstand is 5N show whether or not it is possible for the radius of the path of the bob to be 300mm

Ans= 2.5N(maxtension) and 460mm (max radius)