Verification needed - Rollar Coaster

[rkslperez04]

Bare with me guys as I enlist your help through this worksheet. I really want to get a good grade on this upcoming test and this worksheet is our study guide.

I think I have the hang off it but I want to make sure I am grasping the questions here.

A rollar coaster is traveling on a horizontal track at 20 m/s. What is its speed after climbing the second hill.

I understand this to be an Ei=Ef problem.

Here is my work:

1/2MVi^2 = 1/2MVf^2 + GH ( all the mass variables cancel out )
1/2(20)^2 = 1/2(Vf)^2 + (9.8)(15)
200 = 1/2(Vf)^2 + 147
53 = 1/2(Vf)^2
53*2 = Vf^2
106 = Vf^2
Sq rt 106 is 10 m/s = Vf



am I close? Please let me know.. I want the right answer but I also want to comperhend what's going with these. Just wanted you to know I am not looking for someone to do my work.. just nudge me along ;)

(got one for you too after this, also... a coeffencient of friction.. that one I will need someone to walk me through)

 

[neutrino]

Please provide the complete question when seeking help. Without having any info about "the second hill," we can't do much. One can only assume that it's peak is at a height of 15m above the horizontal track from your work. If that is so, your work is right. You may want to be a little more accurate with the final answer, though (to one or two decimal places).

 

[rkslperez04]

LOL.. I thought the same thing about this question.. as with most..LOL

That was the entire question. You can see my fret over this problem..

With the decimals places I would say 10.0 instead of 10 ??

Looks good though??

 

[neutrino]

LOL.. I thought the same thing about this question.. as with most..LOL

That was the entire question. You can see my fret over this problem..

So where did you get that 15 from?

With the decimals places I would say 10.0 instead of 10 ??

Looks good though??

I actually meant something like 10.2 or 10.29, which is a better approximation to sqrt(106) than 10 is.

 

[rkslperez04]

ohh.. I see.. the second hill is 15m high.. i apolize for that.

Does my work look right?