Maths & Physics Help

[X Abdulrahman X]

Physics>May/June 08>P3(First Variant Question Paper)

Question 8, (c)

The three 60W lamps are replaced by 3 energy-saving ones, that give the same light output buy are rated at only 15W each.

Calc,
(i) The total reduction in power...
(ii) the energy saved when the lamps are lit for 1hr...

Could someone explain this with the working out pls, only the answers are written in the mark scheme. Thank You

[emi]

c) i - total reduction in power:

first calculate both the powers before and after
P1 before replacing:   60x3= 180w
P2 after replacing:     15x3= 45w
      subtract          ____________
                                      135 w   is the reduction in power

ii)  energy saved when lights are lit for one hour
calculate the energy while using 3 ,60w lamps =  VIT = 60x3x3600 = 64000
calculate the engery while using 3, 15w lamps = VIT = 15x3x3600 =162000
                                                                  subtract            __________
                                                                                           486000 J   energy saved  468 KJ

[X Abdulrahman X]

Thank You emi ur seriously amazing 
looks like u will do well in ur physics

[emi]

inshallah

[emi]

plz help me with this Question : its from my text book ..

Q- a 3kW electric heater is used to heat up 2.5kg of water of specific latent heat  capacity 4200J/kg/c . the initial temp is 16 degree. Work out the final temp. after the heater has been switched on for 2 minutes ?


wats the way to solve this  plz someone

[astarmathsandphysics]

McT=Pt so T=Pt/Mc=3000*120/2.5*4200=34.3 this is the increase in pens so add on the initial temp

[zbzbzb25]

go to
this site

www.mathsandphysics.com
 they hav quite a lot of notes

[X Abdulrahman X]

Math > oct/nov 08 > p4
Question 5 b (i+ii)

Might sound like a stupid question but how do we do it ? >.<

[astarmathsandphysics]

Draw a horizontal line from B to A. The angle between this line and the line AB is 10 degrees by the z rule then the bearing is 360-(10+90)=260

C from B 360-(10+90+115)=145

[X Abdulrahman X]

aha got it tyvm m8

[june]

Please i need help with these math questioons, with explanation on how u did it.. thanksssssssssssss

Nov 07 p2 Q12: A and B are sets write the following sets in thier simplest form
a) A n A'
b)A u A'
c) (A u B) U (A n B')

16a) A car manufacturer sells a similar, sclale model of one of its real cars
a) the fuel tank of the real car has a volume of 64litres and the fuel tank of the model has a volume of 0.125 litres.. show that the length of the real car is 8 times the length of the model car

May june 08 p2 q21..
http://www.freeexampapers.us/IGCSE/Maths/CIE/2008%20Jun/0580_s08_qp_2.pdf
NOT TO
SCALE
N
ABCD, BEFC and AEFD are all rectangles.
ABCD is horizontal, BEFC is vertical and AEFD represents a hillside.
AF is a path on the hillside.
AD = 800 m, DC = 600 m and CF = 200 m.
(a) Calculate the angle that the path AF makes with ABCD.
Answer(a) [5]
(b) In the diagram D is due south of C.
Jasmine walks down the path from F to A in bad weather. She cannot see the path ahead.
The compass bearing she must use is the bearing of A from C.
Calculate this bearing.
Answer(b) [3]

[astarmathsandphysics]

Am on a mobile phone. Can someone attempt it. Wont be home until later

[hyebyekadal]

Hey guys I did this MCQ paper and I got everything EXCEPT this question.  I really don't understand why the answer is C. I thought the answer was D. Thanks in advance!
P.S. I have attacehd this particular question if you haven't noticed yet!

[Christy]

Please i need help with these math questioons, with explanation on how u did it.. thanksssssssssssss

Nov 07 p2 Q12: A and B are sets write the following sets in thier simplest form
a) A n A'
b)A u A'
c) (A u B) U (A n B')

16a) A car manufacturer sells a similar, sclale model of one of its real cars
a) the fuel tank of the real car has a volume of 64litres and the fuel tank of the model has a volume of 0.125 litres.. show that the length of the real car is 8 times the length of the model car

May june 08 p2 q21..
http://www.freeexampapers.us/IGCSE/Maths/CIE/2008%20Jun/0580_s08_qp_2.pdf
NOT TO
SCALE
N
ABCD, BEFC and AEFD are all rectangles.
ABCD is horizontal, BEFC is vertical and AEFD represents a hillside.
AF is a path on the hillside.
AD = 800 m, DC = 600 m and CF = 200 m.
(a) Calculate the angle that the path AF makes with ABCD.
Answer(a) [5]
(b) In the diagram D is due south of C.
Jasmine walks down the path from F to A in bad weather. She cannot see the path ahead.
The compass bearing she must use is the bearing of A from C.
Calculate this bearing.
Answer(b) [3]

i am not that good at sets soo im really sorry pal

Q16a) its basically similarity

.125/64 = (x/8) cube

its a basic known this when its a volume its --> volume A/ volume B = (length or height A / length or height B) cube the bracket

and the same for area only u sq. it not cube it

Q21) a) Wht their asking for it FAC

sq. root (800sq+600sq) = 1000

Tan Q= 200/1000

Q = 11.3

b) ok work with me cause this is really difficult ....

i put up an image to help u image ... sorry if its messy ... ill just do the working here ... hope u under stand

we can do tan cause we need angle DCA

tan Q = 800/600

Q = 53.13

add 180 to that cause they want the bearing ... so its adds up to 233.13

[Christy]

sorry its upside down

here