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Author Topic: All Mechanics DOUBTS HERE!!!  (Read 85757 times)

**RoRo**

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Re: All Mechanics DOUBTS HERE!!!
« Reply #450 on: May 12, 2011, 02:52:11 pm »
Quote from: ~~!$!HUSH!$!~~ on May 12, 2011, 05:33:09 am
The secret are you edexcel?
and By the way in MJ 2011 P41 the meu(u) was over one, my teacher told me its correct but it can never go beyond 1,so this was a trick?
Last thing is that how do u calculate squared trigonometry fuction,eg:
tan^2(Theta)= -0.56

Yupp, I am Edexcel and I assume the paper you're talking about is CIE!
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**RoRo**

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Re: All Mechanics DOUBTS HERE!!!
« Reply #451 on: May 12, 2011, 03:01:23 pm »
Can someone please explain to me how do you solve Q7d in January 2010, Q7c in January 2008, Q7f in January 2007 [Edexcel papers]?

Thank you  ;D
« Last Edit: May 12, 2011, 05:17:36 pm by The Secret »
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Offline cashem'up

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Re: All Mechanics DOUBTS HERE!!!
« Reply #452 on: May 12, 2011, 04:56:53 pm »
A light elastic string of natural length 1.6m has modulus of elasticity 100N. One end of the string
is attached to a fixed point. A particle of mass 4 kg is attached to the other end. Find the extension,
e metres, of the string when the particle hangs freely in equilibrium at E.[2]

When the particle is in equilibrium at E, it is given a blow of impulse 20Ns vertically downwards.
Show that, while the string remains taut, the motion of the particle is simple harmonic, and find the
period and amplitude of this simple harmonic motion. [8]

Find also the time that elapses between the blow and the instant when the string first becomes slack.
[4]

The first part is easy to get... but i am having difficulties in the subsequent parts... please help
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Offline leebux101

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Re: All Mechanics DOUBTS HERE!!!
« Reply #453 on: May 12, 2011, 05:37:55 pm »
MJ 2003 P4, q 5 ii . PLEASE ASAP!
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elemis

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Re: All Mechanics DOUBTS HERE!!!
« Reply #454 on: May 13, 2011, 11:01:40 am »
Quote from: Bakhtawar on May 12, 2011, 05:37:55 pm
MJ 2003 P4, q 5 ii . PLEASE ASAP!

Consider the two particles to be one single particle of mass 0.4 kg.

Hence,

0.4*10 - (0.4+0.2) = 0.4*a

a = 8.5

Now consider only one of the particles (I will use particle B) :

B has its weight acting downwards, tension upwards and air resistance of force 0.2 N.

Keeping in mind that B is accelerating at 8.5 m/s2 can you calculate the tension ?
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Offline HUSH1994

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Re: All Mechanics DOUBTS HERE!!!
« Reply #455 on: May 13, 2011, 11:41:19 am »
MJ 2011 P41 the meu(u) was over one, my teacher told me its correct but it can never go beyond 1,so this was a trick?
Last thing is that how do u calculate squared trigonometry fuction,eg:
tan^2(Theta)= -0.56
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Offline The Golden Girl =D

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Re: All Mechanics DOUBTS HERE!!!
« Reply #456 on: May 13, 2011, 12:19:33 pm »
Quote from: The Secret on May 12, 2011, 03:01:23 pm
Can someone please explain to me how do you solve Q7d in January 2010, Q7c in January 2008, Q7f in January 2007 [Edexcel papers]?

Thank you  ;D

Jan 08 ; Q.7]c)  the fact that you ignored the mass/weight of the particles A and B.  

for such Questions I suggest you read chapter one in the book *the ones with only words and definitions*

Jan 07 : Q.7]f)

16:00 - 14:00 = 2 hrs

at 16:00  , t = 2hrs

11i + (17+10) j

rShip = 11i = 27j

S from R  i.e. RS

RS = rShip - rrock

= (11i + 27j ) - (8.5 + 23 j )
= (2.5 + 4j )

distance RS = square root of (2.52) + (42)

Distance RS = 4.72 Km
« Last Edit: May 13, 2011, 12:22:22 pm by ~ The Golden Girl ~ »
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**RoRo**

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Re: All Mechanics DOUBTS HERE!!!
« Reply #457 on: May 13, 2011, 12:54:42 pm »
Quote from: ~ The Golden Girl ~ on May 13, 2011, 12:19:33 pm
Jan 08 ; Q.7]c)  the fact that you ignored the mass/weight of the particles A and B.  

for such Questions I suggest you read chapter one in the book *the ones with only words and definitions*

Jan 07 : Q.7]f)

16:00 - 14:00 = 2 hrs

at 16:00  , t = 2hrs

11i + (17+10) j

rShip = 11i = 27j

S from R  i.e. RS

RS = rShip - rrock

= (11i + 27j ) - (8.5 + 23 j )
= (2.5 + 4j )

distance RS = square root of (2.52) + (42)

Distance RS = 4.72 Km

I think you've solved the wrong questions,

For Q7c in Jan 2008, the question was find the speed of A as it reaches P!

& for 7f in Jan 2007, it's a question from Dynamics not vectors
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Offline leebux101

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Re: All Mechanics DOUBTS HERE!!!
« Reply #458 on: May 13, 2011, 04:27:31 pm »
Quote from: Ari Ben Canaan on May 13, 2011, 11:01:40 am
Consider the two particles to be one single particle of mass 0.4 kg.

Hence,

0.4*10 - (0.4+0.2) = 0.4*a

a = 8.5

Now consider only one of the particles (I will use particle B) :

B has its weight acting downwards, tension upwards and air resistance of force 0.2 N.

Keeping in mind that B is accelerating at 8.5 m/s2 can you calculate the tension ?
yes thankyou sooooo much! =D =D
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Offline leebux101

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Re: All Mechanics DOUBTS HERE!!!
« Reply #459 on: May 13, 2011, 04:29:24 pm »
ON 2009 P41 q4 , all of it, and can u please explain with a diagram of resolved forces please? =d
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Offline 8T

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Re: All Mechanics DOUBTS HERE!!!
« Reply #460 on: May 13, 2011, 06:40:06 pm »
Hello :)
Could someone help out in the following questions ?
M1 Jan O8 
4 C
6 b c d
7 all of it
I know they are many but please if anyone could explain how we solve them ?
Thanks in advance :D
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Offline 8T

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Re: All Mechanics DOUBTS HERE!!!
« Reply #461 on: May 13, 2011, 07:02:46 pm »
Quote from: leebux101 on May 13, 2011, 04:29:24 pm
ON 2009 P41 q4 , all of it, and can u please explain with a diagram of resolved forces please? =d

This edexcel right ?
Do you mean May or Jan 2009 ???
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Offline leebux101

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Re: All Mechanics DOUBTS HERE!!!
« Reply #462 on: May 13, 2011, 07:14:59 pm »
no i mean for CIE, and october november session
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Offline HUSH1994

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Re: All Mechanics DOUBTS HERE!!!
« Reply #463 on: May 14, 2011, 06:39:49 am »
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Offline Naruto123

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Re: All Mechanics DOUBTS HERE!!!
« Reply #464 on: May 14, 2011, 02:11:42 pm »
Hey guyz
like i knw the forces tension nd recently thrust arre there any oder such forces found in connected particles ?

and plz wid a diagram can som1 explain thrust (pushing force) clearly

thanku
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