the greatest acceleration or deceleration that a train may have is a the minimum time in which the train can start from one station to stop at the next ( at a straight distance of s ) is??

Question

anonymous · Answer

options are root s/a         root 2s/a       1/2roots s/a        2 root s/a

anonymous · Answer

option c is correct but can anyone solve this

inkyvoyd · Answer

ok. Let me see.

anonymous · Answer

ok plzzz go on...

inkyvoyd · Answer

What's the formula for kinetic energy?

anonymous · Answer

Ek=mv^2/2

anonymous · Answer

hey we have to solve this my kinematics equation (motion)

inkyvoyd · Answer

And, what's the formula for accleration? v=at right?

anonymous · Answer

v=u+at

inkyvoyd · Answer

$\huge E_k=\frac{mv^2}{2}$

inkyvoyd · Answer

But, $\huge v=at$

dumbcow · Answer

distance = rate*time
--> t = d/r
rate = velocity = a*t

--> t = s/at
--> t^2 = s/a
--> t = sqrt(s/a)

inkyvoyd · Answer

So.
$\huge E_k=\frac{m(at)^2}{2}$

inkyvoyd · Answer

$E_k$ is a constant.

inkyvoyd · Answer

So is m.

anonymous · Answer

plzzz guys use kinemaics equation

inkyvoyd · Answer

Which one?

inkyvoyd · Answer

$\Delta x=V_0t+\frac{1}{2}at^2$?

dumbcow · Answer

kinematic equations...this is why i stick with just math...i showed you  the answer

inkyvoyd · Answer

Wait, I got it. I'm so silly.

inkyvoyd · Answer

$s=V_0t+\frac{1}{2}at^2$
Remember how to find the vertex of a quadtratic equation?

anonymous · Answer

i think we have to use s=ut+1/2 at^2

anonymous · Answer

yes plzz go on inkyvoyd

inkyvoyd · Answer

Now.
the vertex of a quadtratic is at
$\huge (-\frac{1}{2a},-\frac{D}{4a})$
where $D=\sqrt{b^2-4ac}$

anonymous · Answer

then

anonymous · Answer

can u give the answer completely... plzz

inkyvoyd · Answer

Eh, I don't hav eit, @shameer1

anonymous · Answer

i cant understand what u have written

inkyvoyd · Answer

I can't either.

anonymous · Answer

oh....ohh....no

inkyvoyd · Answer

Let me think :S

inkyvoyd · Answer

I'm not sure I understand the problem

inkyvoyd · Answer

Can you restate it?

anonymous · Answer

what???

inkyvoyd · Answer

"the greatest acceleration or deceleration that a train may have is a the minimum time in which the train can start from one station to stop at the next ( at a straight distance of s ) is??
what does "may have is a the minimum time in which the train can start from one station to stop at the next" mean?

anonymous · Answer

"the greatest acceleration or deceleration that a train may have is a.   the minimum time in which the train can start from one station to stop at the next ( at a straight distance of s

inkyvoyd · Answer

oooh

anonymous · Answer

ok leave this i  will  post another question