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As physics p1 MCQS YEARLY ONLY.

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As stated in the question, the liquid in vessel P is twice as dense as the liquid in vessel Q.
We know that pressure = density × acceleration due to gravity × height/depth.
So pressure in P = 2×density×acceleration due to gravity × height
Pressure in Q = density×acc. Due to gravity × height
By taking the the ratio of the quantities we are left with 2\1 I.e A. :)
 
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papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s13_qp_11.pdf

ques 35 please..


papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s13_qp_12.pdf
quest 23 and 27

thanks :)
 
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I want you to check out my signature.. :) Its really helpful
If you don't know many concepts than visit Khan academy :)
So here is your solutions, sorry for late as I was on date with chemistry ;)


10)
Does weight change if a force is exerted on it?
No - Basic thing :) Answer would not change :)


35)
Whats wrong, we just need to compare :¬

For original wire :
Area = Π * r ^ 2 right ? ( I assumed d/2 as r )
length = l
resisitivity = ρ
Resistance = R

For replacement wire :
Area = Π * 4r ^ 2
length = l
resistivity = 2ρ

Now compare original with replacement wire :
Original :
ρl/Π * r ^ 2 --> R

so for replacement wire :
2ρl/ Π * 4r ^ 2 = R/2


37) This was also an easy one ;)
  1. After voltage passes through some resistance it will decrease
  2. The higher the resistance the greater the decrease in voltage
-->So it will decrease less after passing through 2 ohm than when passing through 4 ohm
Hence it is D

ote="Zepudee, post: 814292, member: 97182"]http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_12.pdf

Q8,36? :D ANYONEEEE
8)
I hope that your are familiar with Equations for linear motion. ( Do not confuse with Newton's laws of motion). They are:
1) v = u + a*t
2) s = u*t + 1/2 *a*t^2
3) 2*a*s = v^2 - u^2
Here v stands for final velocity, u stands for initial velocity, s means displacement, t stands for time and a means acceleration.
We are given that:
t = 0.5 seconds
a= 9.8 meters per second square ( As the experiment is taking place on earth, so we consider acceleration due to gravity)
u = 0 ( as the feather is dropped from rest )
Now we apply second equation of motion.
s = u*t + 1/2 *a*t^2
s = 0*0.5 + 1/2*(9.8)*0.5*0.5
s = 1.225 m, which is approximately 1.3.

36) This is also a concept, we dont have fix values of currents, it varies, so we took a mean of power :)

Find power at -1 and then at 2
For -1 :
P = 100W
For 2 :
P = 400W

Now as current is varying we have to take mean value of power : i.e 400 +100 = 500 / 2 = 250W

Shamajh aya :p ?
Just be calm when you solve physics, they have so many easy twists :)[/quote]

oh my goodness, thanks a lot. Yes i do understand. I mean, I didnt really pay much attention while doing all these questions! Oh my. Oh ya, just a quick question though, for the Q37, I thought as resistance is directly proportional to voltage as the current is constant? Cause current should be the same right in the series circuit? Haha, so yeah, do you get what I am trying to ask?
 
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8)
I hope that your are familiar with Equations for linear motion. ( Do not confuse with Newton's laws of motion). They are:
1) v = u + a*t
2) s = u*t + 1/2 *a*t^2
3) 2*a*s = v^2 - u^2
Here v stands for final velocity, u stands for initial velocity, s means displacement, t stands for time and a means acceleration.
We are given that:
t = 0.5 seconds
a= 9.8 meters per second square ( As the experiment is taking place on earth, so we consider acceleration due to gravity)
u = 0 ( as the feather is dropped from rest )
Now we apply second equation of motion.
s = u*t + 1/2 *a*t^2
s = 0*0.5 + 1/2*(9.8)*0.5*0.5
s = 1.225 m, which is approximately 1.3.

36) This is also a concept, we dont have fix values of currents, it varies, so we took a mean of power :)

Find power at -1 and then at 2
For -1 :
P = 100W
For 2 :
P = 400W

Now as current is varying we have to take mean value of power : i.e 400 +100 = 500 / 2 = 250W

Shamajh aya :p ?
Just be calm when you solve physics, they have so many easy twists :)

oh my goodness, thanks a lot. Yes i do understand. I mean, I didnt really pay much attention while doing all these questions! Oh my. Oh ya, just a quick question though, for the Q37, I thought as resistance is directly proportional to voltage as the current is constant? Cause current should be the same right in the series circuit? Haha, so yeah, do you get what I am trying to ask?[/quote]
LOL NO!
 
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Again, Just a logic. I don't have time, so took credits. :p
But in my way, hope you get it :)

15)
When a total amount of work W is done on any object, the kinetic energy of that object changes by a quantity W - if negative work is done on the object, the kinetic energy changes by a negative amount and if positive work is done on the object it's energy changes by a positive amount.

Suppose you throw an object upwards, gravity is the only force that does any work on the object. That work is negative, so the kinetic energy of the object decreases until the object comes to a stop. When it falls down, gravity does positive work on the system thus increasing it's kinetic energy.

In this case, taking the first situation, the force is constant at magnitude F, over the entire displacement s. Thus, the work done by that force is Fs. By the
Work-Kinetic Energy theorem, this is equal to the increase in kinetic energy of the system. This value is given as 4 Joules (8-4 = change in KE = +4 Joules).

In the upcoming situation, the force is 2F, displaced through a distance 2s. Thus, the total work done is 4Fs. This is also the change in kinetic energy of the object.
From above, we know that Fs is 4 Joules, so 4Fs = 4*4 = 16 Joules increase. From 4 Joules, the increase of 16 Joules takes it to 20 Joules = B.

Numeric way explanation :

When the force = F, and distance = s, work done = Fs.
Since work done = K.E. gain → Fs = 8-4 = 4J
Fs = 4J
So, when force = 2F, and distance = 2s, work done = 2F * 2s →4Fs.
Since Fs = 4J, 4Fs = 4 * 4 = 16 J.
So gain in K.E. = 16 J.
And since the kinetic energy already equals 4 J....the new K.E. = 4 + 16 → 20 J
Hence you get answer as B

26)
As shown in the fig, at time = 18 s, phase diff b/w the 2 waves = 180° or π.
1 wavelength = 360°
So, 1/8 of a wavelength = 360°/8 → 45°.

Phase diff = 180° at 18 s.
So, phase diff = 45° at x.
x = (18 * 45)/180
x = 4.5 s

Or Just you can think it this way :¬

At 18 second, the phase difference in 1/2 of the cycle, so at what time will the phase difference be 1/8? just try normal proportionation

Hence answer is B
 
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As stated in the question, the liquid in vessel P is twice as dense as the liquid in vessel Q.
We know that pressure = density × acceleration due to gravity × height/depth.
So pressure in P = 2×density×acceleration due to gravity × height
Pressure in Q = density×acc. Due to gravity × height
By taking the the ratio of the quantities we are left with 2\1 I.e A. :)
Ah, I misread the marking scheme!! :sleep: Thanks so much for the time, I really appreciate it!
 
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Again, Just a logic. I don't have time, so took credits. :p
But in my way, hope you get it :)

15)
When a total amount of work W is done on any object, the kinetic energy of that object changes by a quantity W - if negative work is done on the object, the kinetic energy changes by a negative amount and if positive work is done on the object it's energy changes by a positive amount.

Suppose you throw an object upwards, gravity is the only force that does any work on the object. That work is negative, so the kinetic energy of the object decreases until the object comes to a stop. When it falls down, gravity does positive work on the system thus increasing it's kinetic energy.

In this case, taking the first situation, the force is constant at magnitude F, over the entire displacement s. Thus, the work done by that force is Fs. By the
Work-Kinetic Energy theorem, this is equal to the increase in kinetic energy of the system. This value is given as 4 Joules (8-4 = change in KE = +4 Joules).

In the upcoming situation, the force is 2F, displaced through a distance 2s. Thus, the total work done is 4Fs. This is also the change in kinetic energy of the object.
From above, we know that Fs is 4 Joules, so 4Fs = 4*4 = 16 Joules increase. From 4 Joules, the increase of 16 Joules takes it to 20 Joules = B.

Numeric way explanation :

When the force = F, and distance = s, work done = Fs.
Since work done = K.E. gain → Fs = 8-4 = 4J
Fs = 4J
So, when force = 2F, and distance = 2s, work done = 2F * 2s →4Fs.
Since Fs = 4J, 4Fs = 4 * 4 = 16 J.
So gain in K.E. = 16 J.
And since the kinetic energy already equals 4 J....the new K.E. = 4 + 16 → 20 J
Hence you get answer as B

26)
As shown in the fig, at time = 18 s, phase diff b/w the 2 waves = 180° or π.
1 wavelength = 360°
So, 1/8 of a wavelength = 360°/8 → 45°.

Phase diff = 180° at 18 s.
So, phase diff = 45° at x.
x = (18 * 45)/180
x = 4.5 s

Or Just you can think it this way :¬

At 18 second, the phase difference in 1/2 of the cycle, so at what time will the phase difference be 1/8? just try normal proportionation

Hence answer is B

Wow, Thank you for typing all this out for me. I really appreciate :) And YUP, i understand now :) Didnt know it is just like that, I kept making it harder for myself.
 
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8)
First calculate accn from first information
V^(2) - U^(2) = 2as
36 - 64 = 14a
a = -2 m/s^(2)

Now find s from same equation
V^(2) - U^(2) = 2as
0^(2) - 6^(2) = 2(-2)s
s = 9m

15)
viscous force - Force that act on a body moving through a fluid that are caused by the resistance of the fluid.
upthrust force - The upward force that a liquid exerts on a body floating or immersed in a liquid.
Gravitational force - Force exerted by one body on another, and is directly proportional to the product of their masses and inversely proportional to the square of the distance separating their center of masses.
So Here W is same in all option so you do not need to look at that
So now look at U that is mostly in liquid so it would be less.. so if you look at options in D it is very less.
So now look at V it would obviously be more, as hailstone is falling just below the cloud that is from the base and vertically towards the ground. Hence in option D viscous force is high
Hence answer is D

21)
There is more pressure near Y due to the height of the column. The water therefore is compressed and thus gains elastic potential energy.
As the rate of flow is constant, kinetic energy is out of the options.
We can say, K.E. doesn't increases because the question states that the rate of flow is constant. E.P.E. increases because pressure increases with depth.

33)
okay so we have a wire and it is being stretched. By stretching a wire you only change its length or area you can't change the volume (to change volume you should either remove a part of it or add more copper to it)
and so Volume of stretched=volume of unstretched

A copper wire had a diameter of 1.0mm and it was stretched to 0.5mm diameter. The word stretched makes it quite clear that the length changes
Now the question is by how much did the length change?
We didn't add extra to it we didn't remove from it so that means we can use ratios

I guess you aren't getting this part
let me use an example. lets say you have got 2 bowls of chocolate each bowl contain 10 so you have a total of 20 it will always stay 20 unless you decide to eat one from it or maybe just add another chocolate to it but that's not happening You decide to pick one chocolate from bowl A and you drop it in bowl B
total number still 20 but there is 1 less in bowl A where did it go? to bowl B!

From our question Bowl A is Diameter and Bowl B is the length and total number is the total volume
You working shows that you did consider the change in Diameter but not length
Well basically if you do that your total will change to 19 and in the length case you are just removing a part of it which is not indicated in the question you are suppose to use the same 'long,stretched' wire .Have you played with play doh? if you have you might have noticed while making a snake or anything long the more you reduce the cross sectional area the longer the snake.

We have to find out the change in area in other words the area which was removed to take shape as a length
I have done a lot of talking lets start with the calculations
First thing first finding the change in area which you did already (y)
Area 1 (pie(0.5)^2 )
Area 2 (pie(0.25)^2 )
you have done it and found the ratio as 4/1
so goes for the length which you ignored
find the initial length using the formula R=resistivity*length/area
but as it is the same material i take resistiviy as 1
0.2=l/pie(1*0.5)^2
l=1/20 pie
this is the initial it should also change by 4/1 as the area did
so final l=(1/20 pie)*(4/1) =(1/5 pie)
now you can use the formula again to get the new R with Area=pie(o.25)^2 and l=(1/5 pie)

35)
I will get back on this.
 
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If der r 2 or more wires protruding from a single point, then da current is split. When current is split, da value of current is not da same everywhere in da circuit. Da only circuit arrangement, where dis is not da case is arrangement D. In D, a single wire is connecting every meter, so current is same throughout circuit
question number ?
 
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