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Author Topic: Edexcel PHYSICS Doubts  (Read 136187 times)

Offline Deadly_king

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Re: Edexcel PHYSICS Doubts
« Reply #405 on: January 11, 2011, 04:54:14 am »
Quote from: Vampire-Love4ever on January 10, 2011, 08:43:34 pm
I have a doubt.

I read from one of my photocopied notes that : the diameter of a wire should be measured using a micrometer screw gauge and calculate area using formula = 1/4*pi*d^2.

Is it right if we use formula: pi*r^2 instead? :S

Sure it,s the same formula. You just changed the values.

d = 2r ------> That's all you need to take care, otherwise the formula remains the same.

Good luck for the exams. :)
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Offline Vampire-Love4ever

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Re: Edexcel PHYSICS Doubts
« Reply #406 on: January 11, 2011, 09:58:57 am »
Quote from: Deadly_king on January 11, 2011, 04:54:14 am
Sure it,s the same formula. You just changed the values.

d = 2r ------> That's all you need to take care, otherwise the formula remains the same.

Good luck for the exams. :)

=O Ok.

Thank you so much for replying! :D
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Offline Malak

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Re: Edexcel PHYSICS Doubts
« Reply #407 on: January 11, 2011, 10:36:17 am »
Can anyone help solve this Question..
thx


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Offline The Golden Girl =D

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Re: Edexcel PHYSICS Doubts
« Reply #408 on: January 11, 2011, 10:57:06 am »
Quote from: ang3l on January 11, 2011, 10:36:17 am
Can anyone help solve this Question..
thx


since the rate of flow = 0.13 ms-1  .... it means the Volume = 0.13 m

Mass/time = 0.13 *1000 = 130 Kg

Gravitational Potential Energy = mgh

 = 130 * 9.81 * 30   ...blue is the Delta h *change in height*
 = 38,259 J

Power = Work done or engery / Time
         = 38,259 / 1
         = 38,259 J
 
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Offline Assi1993

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Re: Edexcel PHYSICS Doubts
« Reply #409 on: January 11, 2011, 12:24:17 pm »
hello
can some1 plz tell me that how will we draw the graph for this???

thanks in advance.....!
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Offline Deadly_king

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Re: Edexcel PHYSICS Doubts
« Reply #410 on: January 11, 2011, 12:41:36 pm »
Quote from: Assi1993 on January 11, 2011, 12:24:17 pm
hello
can some1 plz tell me that how will we draw the graph for this???

thanks in advance.....!

You just need to know this formula ----> F = ke and e = RL/A

From the second equation, e is proportional to L. This means that doubling the length will double the extension. So the curve is likely to bend at 0.5m rather than 0.25m. (Graph L)

In the second case, we can note that e is inversely proportional to cross-sectional area. So by multiplying the area by 3, we need to reduce the extension by 3 (e/3). So curve bends at around 0.25/3 = 0.08m. (Graph A)

In both cases same type of curve applies. :)

Hope it helps :D
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Offline Assi1993

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Re: Edexcel PHYSICS Doubts
« Reply #411 on: January 11, 2011, 02:32:08 pm »
got it :D
thankYou soooo much!!!!! :)
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Offline Vampire-Love4ever

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Re: Edexcel PHYSICS Doubts
« Reply #412 on: January 11, 2011, 02:50:55 pm »
why do we add the drag and not minus it???
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Offline Vampire-Love4ever

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Re: Edexcel PHYSICS Doubts
« Reply #413 on: January 11, 2011, 02:54:27 pm »
Q-A hot air ballon is rising vertically at a speed of 10ms^-1. An object is released from the balloon. Graph shows how the velocity if the object varies with time from when it leaves the balloon to when it reaches the ground 4s later. It's assumed that the air resistance is neglected.

(i) Determine the object's final displacement from it's point of release from the balloon. [2]


Mark scheme answer:

rise 5m and fell 5m [1]

displacement 40m before point of release [1]
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Offline Malak

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Re: Edexcel PHYSICS Doubts
« Reply #414 on: January 11, 2011, 02:57:02 pm »
Quote from: Vampire-Love4ever on January 11, 2011, 02:50:55 pm
why do we add the drag and not minus it???

i think thats because u need to find the Total FORCE from which when u minus the resultant, you will get the drag=430 N..

Hope u get it?
« Last Edit: January 11, 2011, 02:59:26 pm by ang3l »
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Offline Vampire-Love4ever

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Re: Edexcel PHYSICS Doubts
« Reply #415 on: January 11, 2011, 02:57:32 pm »
how to do part c???
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Offline Vampire-Love4ever

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Re: Edexcel PHYSICS Doubts
« Reply #416 on: January 11, 2011, 03:03:59 pm »
why isnt the answer B ?

Isn't stoke's law applicable to object in laminar flow? ? ?
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Re: Edexcel PHYSICS Doubts
« Reply #417 on: January 11, 2011, 03:08:05 pm »
Quote from: Vampire-Love4ever on January 11, 2011, 03:03:59 pm
why isnt the answer B ?

Isn't stoke's law applicable to object in laminar flow? ? ?

To be honest I never heard of stoke's law applying to a certain thing ONLY. Which is Why I think it shouldn't be B *I'll ask for back up :) *
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Offline Vampire-Love4ever

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Re: Edexcel PHYSICS Doubts
« Reply #418 on: January 11, 2011, 03:10:10 pm »
Quote from: Miss Invisible on January 11, 2011, 03:08:05 pm
To be honest I never heard of stoke's law applying to a certain thing ONLY. Which is Why I think it shouldn't be B *I'll ask for back up :) *

In my Edexcel revision guide it's written: Stoke's law appiled to small spherical object moving at low speed in laminar flow.

I agree with A but I am lil confused cos I am stuck with both A and B. :/
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Offline Malak

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Re: Edexcel PHYSICS Doubts
« Reply #419 on: January 11, 2011, 03:14:40 pm »
Quote from: Vampire-Love4ever on January 11, 2011, 03:10:10 pm
In my Edexcel revision guide it's written: Stoke's law appiled to small spherical object moving at low speed in laminar flow.

I agree with A but I am lil confused cos I am stuck with both A and B. :/

By laminar flow i think it means for the velocity to be terminal..
And as it says SMALL speherical objects...the answer is possibly A
i dnt knw..Mayb A is more reasonable thts y
« Last Edit: January 11, 2011, 03:19:23 pm by ang3l »
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