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A-Level Physics Paper 1 doubts (MCQ)

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NidZ- Hero:
Some one xeplain me the steps

elemis:
Give me a few minutes.

elemis:
You can write two formulas from the given data :

S1 = ut +0.5at2

S1+S2 = u(2t) +0.5a(2t)2

S1+S2 = 2ut + 2at2

Now, notice all the answers have S1, S2 and time.... Initial velocity has been eliminated. So we know we have to play around with the second equation.

Using the first equation :

ut = S1 -0.5at2

Substitute into the second one :

S1+S2 = 2*(S1 -0.5at2) + 2at2

Simplifying :

S1+S2 = 2S1 - at2 +2at2

S2-S1 =  at2

(S2-S1)/t2 = a

Answer = A

Ghost Of Highbury:

--- Quote from: NidZ- Hero on June 04, 2011, 08:19:28 am ---Some one xeplain me the steps

--- End quote ---

s1 = ut + 0.5at^2

u = (2s1 - at^2)/2t

2. s1+s2 = 2ut + 2at^2    (Because it takes time 2t to cover a distance of s1+s2)

u = (s1+s2-2at^2)/2t

Equate both the Us

(2s1-at^2)/2t = (s1+s2-2at^2)/2t

2t gets cancelled

2s1-at^2-s1-s2+2at^2 = 0
a = (s2-s1)/t^2

Ghost Of Highbury:
Ah, sry, my bad.

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