A roller coaster makes a run down a track from a vertical distance of 25m. If there is negligible friction and the coaster starts from rest, what is its speed at the bottom of the track?
Please

Question

A roller coaster makes a run down a track from a vertical distance of 25m. If there is negligible friction and the coaster starts from rest, what is its speed at the bottom of the track?
Please

loser66 · Answer

@DemolisionWolf

anonymous · Answer

so no forces but gravity, so, free-fall from rest.
it 'falls' 25m
can you see which kinematic equation to use now?

loser66 · Answer

W = mgh?

loser66 · Answer

or K =1/2mv^2?

anonymous · Answer

awhh, so your exam is on energy, kinematics and momentum and newtons forces I take it?

anonymous · Answer

we'll want to use the kinematic equations for this one.
energy uses 'mass' and we arn't given mass.
V = V + at
v^2 = v^2 + as
s = s + vt + (1/2)at^2
so which of these 3 kinematic equations do you know all the variables Except the one you are looking for [velocity]

anonymous · Answer

haha, no i'm not in your class ^_^

i'm you professor!

lol

loser66 · Answer

hey, why?? W = $\triangle K$ and W = mgh, where K = 1/2mv^2
we cancel out m, no need to have m, right?

loser66 · Answer

Ok @DemolisionWolf  my prof !!! hehehe... you are not lucky at all when you have a student like me.

anonymous · Answer

haha, I see it now, i'm so use to solving 'free-fall' equations with kinetics, not with energy! yaya, you guys are totally right, energy works! 
weird as it is, the two equations end up looking identical

loser66 · Answer

I am sorry "prof". hehehe.... I will fire back if you say something nonsense to me.

anonymous · Answer

haha
I gotta take off, 
good luck on your exam!