:eek:very hard stuff ..need help please

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- Jul 15th 2007, 11:27 AMcarlasaderdistance problem
:eek:very hard stuff ..need help please

- Jul 15th 2007, 12:26 PMjanvdl
b) $\displaystyle v^2 = u^2 + 2as $

$\displaystyle 1296 = + (2)(2)(s) $

$\displaystyle s = 324 $

$\displaystyle s = ut + \frac{1}{2} a t^2 $

$\displaystyle s = ut \ (There \ was \ no \ acceleration) $

$\displaystyle s = (36)(90) $

$\displaystyle s = 3240 $

$\displaystyle v^2 = u^2 + 2as $

$\displaystyle 0 = 36^2 + (2)(-3)(s) $

$\displaystyle s = 216 $

Add all those distances together and you get: 3780 metres :) - Jul 15th 2007, 12:27 PMjanvdl
c) T2 takes 150s to complete the journey.

I calculated T1 to take only 118s.

But they travelled the same distance and route. Im guessing that Train 1 was therefore faster. Maybe it had a bigger average speed.

d) For T2

s = 3870

t = 150

u = 0

v = 0

a = ?

$\displaystyle s = ut + \frac{1}{2} a t^2 $

$\displaystyle 3870 = \frac{1}{2} a 150^2 $

$\displaystyle a = \frac{43}{125} $

$\displaystyle v = u + at $

$\displaystyle v = 0 + \frac{43}{125} (150) $

$\displaystyle v = 51,6 ms^-1 $