Physics: Post your doubts here!

[agha saad 22]

It's kg/s. And khud try ker k nikala hai Though search it online, zarur hoga.. Kg/m^3 *m/s = kg/m^2 s.This means, one kg per second per m^2 of area. Just multiply with the number of m^2 (area) you have and you get kg/s on that specified area.

(Y) nice try!! is ka matlab!! kuch samaj na ayee values ko multiply kar do.. just kidning!!! Weldone (Y)

 

[Suchal Riaz]

POINTER !

some of it is pencil

 

[agha saad 22]

It's kg/s. And khud try ker k nikala hai Though search it online, zarur hoga.. Kg/m^3 *m/s = kg/m^2 s.This means, one kg per second per m^2 of area. Just multiply with the number of m^2 (area) you have and you get kg/s on that specified area.

btw aaisa question like har baar ata hai

 

[♣♠ Magnanimous ♣♠]

thanks man.

summer 2013 practicals 33
readings only
https://www.dropbox.com/s/sokx40nb7zdzuc8/S13-33.pdf

 

[Thought blocker]

some of it is pencil

I'll wait for my doubts to be solved, MATH! p1 Do it ASAP

 

[Suchal Riaz]

i made a mistake in calculating 1/l in 5th and 6th reading. sorry i should have checked first

 

[Suchal Riaz]

I'll wait for my doubts to be solved, MATH! p1 Do it ASAP

which paper it is?

 

[Thought blocker]

i made a mistake in calculating 1/l in 5th and 6th reading. sorry i should have checked first

np Suchal!

 

[usama321]

btw aaisa question like har baar ata hai

yup, it's a common formula, though i didn't know about it when i first tried the question

 

[Thought blocker]

which paper it is?

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s10_qp_12.pdf

 

[sitooon]

Can someone Help with Graph : question 9b(ii)

 

[Suchal Riaz]

Sorry another mistake. Eveything had to be in one decimal place. I don't know what was i thinking when i was in lab.

 

[meerul264]

Help me with my superposition doubt please.

What changes is observed when the following is increased?
1. slit separation, a
2. slit width, w
3. angle of diffracted light from zero order, t
4. wavelength, l
5. perpendicular distance between the slit and screen, D

thanks

 

[amal sharkawi]

A wind turbine has blades that sweep an area of 2000 m
2. It converts the power available in the

wind to electrical power with an efficiency of 50%.
What is the electrical power generated if the wind speed is 10 m s
–1? (The density of air is

1.3 kg m
–3.)

A
130 kW B 650 kW C 1300 kW D 2600 kW
can anyone explain this question

 

[Thought blocker]

A wind turbine has blades that sweep an area of 2000 m
2. It converts the power available in the

wind to electrical power with an efficiency of 50%.
What is the electrical power generated if the wind speed is 10 m s
–1? (The density of air is

1.3 kg m
–3.)

A
130 kW B 650 kW C 1300 kW D 2600 kW
can anyone explain this question

mass flow rwte intercepted by wind turbine blades is 2000*10*1.3=26000 kg/sec
energy=1/2* 26000 * 100 Joules/sec or watts.
due to 50% efficiency,power produced is half of that. Divide by 1000 o express in KW
Yahoo answer.

 

[amal sharkawi]

The diagram shows a wheel of circumference 0.30 m. A rope is fastened at one end to a force
meter. The rope passes over the wheel and supports a freely hanging load of 100 N. The wheel is
driven by an electric motor at a constant rate of 50 revolutions per second.
When the wheel is turning at this rate, the force meter reads 20 N.
load 100N
force
meter
25

20
15
10
5
0
50rev s
–1

wheel of
circumference 0.30m
N
What is the output power of the motor?
A
0.3 kW B 1.2 kW C 1.8 kW D 3.8 kW
any one can explain this question

 

[amal sharkawi]

A light wave of amplitude
A is incident normally on a surface of area S. The power per unit area

reaching the surface is
P.

The amplitude of the light wave is increased to 2
A. The light is then focussed on to a smaller

area
. 3

1
S

What is the power per unit area on this smaller area?
A
36P

B
18P

C
12P

D
6P

can any one explain this

 

[Suchal Riaz]

The diagram shows a wheel of circumference 0.30 m. A rope is fastened at one end to a force
meter. The rope passes over the wheel and supports a freely hanging load of 100 N. The wheel is
driven by an electric motor at a constant rate of 50 revolutions per second.
When the wheel is turning at this rate, the force meter reads 20 N.
load 100N
force
meter
25

20
15
10
5
0
50rev s
–1

wheel of
circumference 0.30m
N
What is the output power of the motor?
A
0.3 kW B 1.2 kW C 1.8 kW D 3.8 kW
any one can explain this question

It wpuld be better if you would just tell me the question number and year of paper.

 

[asma tareen]

http://www.mediafire.com/view/8x75fx0uun11t9o/9702_p1_current_electricity_all.pdf
Q2 can anyone tell me what does increasing with factor of 16 means :/?

 

[Suchal Riaz]

it means its resistance increase 16 times. means it became 16R from R
P=V²/R
R=V²/P=(240)²/100=576 ohm
increased R = 16*576=9216 ohm
D is answer
asma tareen