unknown123
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#1
Could somebody check if the answers to these questions are correct?

1)an object of single substance with mass 10kg and moving horizontally with speed 10m^-1 hits a wall and stops. internal friction cause the object to increase temperature by 0.1k. find specific heat capacity, in Jkg^-1K^-1.

o.5mv^2= ∆U

∆U = C∆T

500= ∆U

C∆T= 500
C∆T =mc∆T
500= mc∆T
c= 500 Jkg^-1K^-1.




2) a car of mass 1000kg is initially at vertical heigh h1= 10 metres and is moving down a slope, with the engine off, at initial speed 10ms^-1. The brakes are used, causing an increase in internal energy of 1.3 x 10^5 J and the car comes to a rest at vertical heigh h1. find h1, assuming no other effects occur.

g= 10m s^-2

∆E = ∆Ek + ∆Ep + ∆U
∆E=0
∆Ek + ∆Ep = -∆U
5000+ 10000(h1-10)= 1.3 x 10^5
h1=2.5 metres
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Stonebridge
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#2
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#2
(Original post by unknown123)
Could somebody check if the answers to these questions are correct?

1)an object of single substance with mass 10kg and moving horizontally with speed 10m^-1 hits a wall and stops. internal friction cause the object to increase temperature by 0.1k. find specific heat capacity, in Jkg^-1K^-1.

o.5mv^2= ∆U

∆U = C∆T

500= ∆U

C∆T= 500
C∆T =mc∆T
500= mc∆T
c= 500 Jkg^-1K^-1.




2) a car of mass 1000kg is initially at vertical heigh h1= 10 metres and is moving down a slope, with the engine off, at initial speed 10ms^-1. The brakes are used, causing an increase in internal energy of 1.3 x 10^5 J and the car comes to a rest at vertical heigh h1. find h1, assuming no other effects occur.

g= 10m s^-2

∆E = ∆Ek + ∆Ep + ∆U
∆E=0
∆Ek + ∆Ep = -∆U
5000+ 10000(h1-10)= 1.3 x 10^5
h1=2.5 metres
1) correct
2) ΔEk = 50,000J
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Skilled
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(Original post by Stonebridge)
1) correct
2) ΔEk = 50,000J
Hey, Is it Ok if you could pleas approve Arsey's thread for the Jan 2013 s1 paper?, Thanks
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Stonebridge
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(Original post by Skilled)
Hey, Is it Ok if you could pleas approve Arsey's thread for the Jan 2013 s1 paper?, Thanks
I'm not sure which thread you mean or what you mean by "approve" it.
If you link to the thread I can check it out.
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Skilled
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(Original post by Stonebridge)
I'm not sure which thread you mean or what you mean by "approve" it.
If you link to the thread I can check it out.
Im not sure why Arsey isn't replying, I think he is offline, but this is the post by him about a moderator's approval:
http://www.thestudentroom.co.uk/show...1#post41111371
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Arsey
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#6
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#6
(Original post by Stonebridge)
I'm not sure which thread you mean or what you mean by "approve" it.
If you link to the thread I can check it out.
I tried to start a thread where I posted the model answers to the S1 exam yesterday.

It was called S1 Edexcel Jan 2013 Post Exam Thread (Model solutions attached)

It said it needed to be approved by a moderator.

I started the thread at about 7:30am and it still hasn't been approved.

None of the other similar threads I posted required approval so I am not sure what is going on.


(this is in the Maths exams forum)
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Stonebridge
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#7
(Original post by Arsey)
I tried to start a thread where I posted the model answers to the S1 exam yesterday.

It was called S1 Edexcel Jan 2013 Post Exam Thread (Model solutions attached)

It said it needed to be approved by a moderator.

I started the thread at about 7:30am and it still hasn't been approved.

None of the other similar threads I posted required approval so I am not sure what is going on.


(this is in the Maths exams forum)
You need to ask a mod in the Maths section.
I'm not a mod (I'm a forum assistant in physics) and have no admin permissions in maths. Sorry. Try "Illusionary" from the mods list.
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