# distance problem

• Jul 15th 2007, 11:27 AM
distance problem
:eek:very hard stuff ..need help please
• Jul 15th 2007, 12:26 PM
janvdl
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 PM
janvdl
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 = ?

$\displaystyle s = ut + \frac{1}{2} a t^2$
$\displaystyle 3870 = \frac{1}{2} a 150^2$
$\displaystyle a = \frac{43}{125}$

$\displaystyle v = u + at$
$\displaystyle v = 0 + \frac{43}{125} (150)$
$\displaystyle v = 51,6 ms^-1$