1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Speed of Rollercoaster

  1. Jul 27, 2011 #1
    1. The problem statement, all variables and given/known data
    The roller-coaster car shown in Fig. 6-41 (h1 = 50 m, h2 = 13 m, h3 = 25 m), is dragged up to point 1 where it is released from rest. Assuming no friction, calculate the speed at points 2, 3, and 4.

    2. Relevant equations
    v2= Square Root of 2*Gravity*Height

    3. The attempt at a solution
    I used the formula to figure out the speed at point 2( which was 31.304 m/s) but it doesn't seem like the same formula works for points 3 and 4 so I'm guessing I need another formula to figure out the other 2 points, although I have no clue what that might be.
  2. jcsd
  3. Jul 27, 2011 #2


    User Avatar
    Homework Helper

    From 1 to 2, the cart is released from rest at maximum height h1.

    So the total energy is the PE at point 1.

    If you want the energy conversion between 1 and 3 then you need to see that the PE at point 3 would include the change in PE from 1 to 3 and the KE at 3.

    Use conservation of energy to get this speed.
  4. Jul 28, 2011 #3


    User Avatar
    Homework Helper

    mis-leading equation here. the reference to height should say "change of height"

    For Point 2, the change of height is h₁

    For point 3, the change of height is (h₁ - h₃)

    For Point 4, the change of height is (h₁ - h₂)

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook