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Physics: Post your doubts here!

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Re: Physics Help here! Stuck somewhere?? Ask here! :)

i hope it helps :%)
 

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Re: Physics Help here! Stuck somewhere?? Ask here! :)

9702_w05_qp1 - Q11, 16 & 26
9702_s06_qp1 - Q33
9702_w06_qp1 - Q25


Thanks!
 
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Re: Physics Help here! Stuck somewhere?? Ask here! :)

unique840 said:
i hope it helps :%)
According to the rules of trigonometry, cos 60* = adj/hyp = W/y
If y = W cos 60* =W^2/y , which doesn't make any sense.
Shouldn't y = W/ cos 60*?
Where am I wrong? :S
 
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Who says that W is adjacent? If you observe, W is actually the hypotenuse. The y and x components of W are actually perpendicular and parallel to the inclined plane, respectively. Whenever you want to find the component of a given slanted force you have to make it the HYPOTENUSE. The components here are with respect to the surface.
 

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hamidali391 said:
Whenever you want to find the component of a given slanted force you have to make it the HYPOTENUSE. The components here are with respect to the surface.
This is exactly what I needed to know. Thank you.
 
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Re: Physics Help here! Stuck somewhere?? Ask here! :)

11. the only force acting on the ball is gravity which is downwards so xv is the direction.
 
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Re: Physics Help here! Stuck somewhere?? Ask here! :)

Guys another question popped up.

A ball is thrown horizontally in still air from the top of a very tall building. The ball is affected by air resistance.
What happens to the horizontal and to the vertical components of the ball’s velocity?

It is from november 2010 paper 13, question 11. please help!!
 
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a021011 said:
9702_w05_qp1 - Q11, 16 & 26
9702_s06_qp1 - Q33
9702_w06_qp1 - Q25


Thanks!

11. the only force acting on the ball is gravity which is downwards so xv is the direction.

Btw i just copied it from the guy who answered my question, so thank him ^^
 
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babycry said:
Guys another question popped up.

A ball is thrown horizontally in still air from the top of a very tall building. The ball is affected by air resistance.
What happens to the horizontal and to the vertical components of the ball’s velocity?

It is from november 2010 paper 13, question 11. please help!!

11. the horizontal component of velocity decreases to zero as air resistance acting so it will reach finally towards zero velocity. Vertical component increases to a constant value towards the Earth. ball falling in the positive direction downwards.
i can't explain in a clear way as my concept on this is also weak.
 
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babycry said:
Guys another question popped up.

A ball is thrown horizontally in still air from the top of a very tall building. The ball is affected by air resistance.
What happens to the horizontal and to the vertical components of the ball’s velocity?

It is from november 2010 paper 13, question 11. please help!!

The horizontal velocity will decrease to Zero and the veritcal velocity will increase until it reaches a constant value. This question involves the concept of terminal velocity. The vertical velocity will increase initially due to the object's weight by as it is countered by drag the velocity will reach a constant value when the object is in vertical equilibrium. Whereas, the horizonal velocity will decrease to zero because of the consistent air resistance.
 
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rviboy said:
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w10_qp_11.pdf
Q.9 , 22, 34

plz anyone...
Q9
2as=v^2-u^2
2ax=0^2-u^2
a=-u^2/(2x)

2as=v^2-u^2
2(-u^2/(2x))=0^2-(1.20u)^2
-(u^2/x)s=-1.44u^2 U^2 and -ve sign cancel
s=1.44x


Q22)
I did this question before in the phy thread, so here is it again.
Let Force exerted by load be W
let K1 be the spring constant of wire X and K2 be the spring constant of wire Y
because wires are joint and of different length and spring constant, different ratio of forces will act on both of them.
Force on X=3/(3+1) W=3/4 W
Force on Y=1/4 W

For the 1st wire:
X:
3/4 W= K1 (1.5)
k1 = 1/2W

Y:
1/4W=K2 (1)
K2=1/4W

For the 2nd wire:
lengths of wires have changes so will the ratio of forces acting on them
X:
1/4W=K1 x1 where k1=1/2W
1/4W=1/2W x1
x1=1/2 mm

Y:
3/4W=K2 x2 where k2=1/4W
3/4W=1/4W x2
x2=3 mm

total extension=x1 + x2= 0.5 + 3= 3.5 mm

Q34)
Find total resistance
resistance on both wires= 0.005 x 800 x 2= 8 Ohms
resistance of relay=16/0.6= 26.67 Ohms
Total resistance = 34.67 Ohms
emf=34.67 x 0.6= 20.8 V
 
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nov 2010 question 9 paper 11

u = initial speed V = final speed = 0 distance = x

0 = u^2 + 2ax so:
2x = -u^2/a
x = -u^2/2a

x= Ku^2 where K is a constant of -1/2a
So x∞u^2

The second train has a speed, u, of 1.2 u

Since x∞u2 ,but u is now 1.2 u

x = u^2
? = (1.2 u)^ 2

When we cross multiply the answer is 1.44x.

Hope i helped :lol: :lol: :lol:
 
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A thermometer can read to an accuracy of 0.5 C
The thermometer is used to measure a temperature rise from 40 C to 100 C

What is the percentage uncertainty in the measurement of temperature rise ?



post answr ASAP ... thanks :D
 

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Re: Physics Help here! Stuck somewhere?? Ask here! :)

mury456 said:
A thermometer can read to an accuracy of 0.5 C
The thermometer is used to measure a temperature rise from 40 C to 100 C

What is the percentage uncertainty in the measurement of temperature rise ?



post answr ASAP ... thanks :D
Assalamoalaikum!

absolute error = 0.5 / 2 = 0.25

%uncertainty = 0.25/(ur reading) * 100
 
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I wanted to ask which paper are we going to give, the practical one for Physics and Chemistry...? The timetable has not mentioned Paper 32... It has only 33 and 34 for the 2012 May June session...
 
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the electron beam is directed at right angles from the observer so it will deflect into the positive end of the shaded area n deflected towards the observer at an angle of 90 degree. its kinda guess..or maybe i think the beam will be reflected after hitting the shaded area towards the observer...it may act at a specific angle nd then go back out of the plane paper...
 
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