(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 250kg roller coaster passes a point A(located at the top of a hill of height 18.0m) at 12.0 m/s.

What is the speed of the roller coaster at point B located at the bottom of the hill if 8500J of energy is transformed to heat during the journey?

2. Relevant equations

ΔE = heat

3. The attempt at a solution

First I wrote down what I knew from reading the question:

m = 250kg

g = 9.0 m/s (squared)

vi = 12.0 m/s

hi = 18.0m

hf = 0m

heat energy = 8000J

Someone showed me how to do this question and they said that since the question only tells you what the mass, initial velocity, initial height, final height, and heat energy are, that you can just use the equation for heat (ΔE=heat).

ΔE = heat

(Epf-Epi) + (Ekf-Eki)=heat

Epf + Ekf = Epi + Eki + heat

mghf + (1/2)mvf(squared) = mghi + (1/2)mvi(squared) + heat

After putting in the numbers and isolating vf, I got a final velocity of about 23.7 m/s. But I was just wondering is this correct, or do I need to find the work and use the equation "Wnc=ΔE" and then use that and my other findings to isolate and find vf? Because this question is out of 10 marks so I was just wondering whether there was more to this question (in the attempt to find vf) calculation wise or was what I did above enough or correct to find the final velocity?

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# Homework Help: Work and energy roller coaster question

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