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: Acceleration on a helix

  1. Apr 25, 2015 #1
    Dear physicist,
    my task is to calculate the acceleration of a particle of mass m which moves without friction in the earth's gravitational field on a helix:
    The helix is parameterized as shown:

    [tex]x(\phi)=a cos \phi[/tex]
    [tex]y(\phi)=a sin \phi[/tex]
    [tex]z(\phi)=c \phi[/tex]

    formed with a radius a,gradient c as constants and the angle [tex]\phi[/tex] which mimics the projection of the radius vector on the x, y plane of the axis x with [tex]\phi \in 0<= \phi<\infty[/tex]

    What is the relationship between the arc length s and the angle phi?
    Also, I need to derivate the tangents, normals and binormal vector by using [tex]\overrightarrow{r}(s)[/tex]
    and calculate the end nor the path velocity (with s (t = 0) = 0, s' (0) = 0).

    I'm afraid not to have any approaches to solve the problem :/
    I would appreciate every hint.
  2. jcsd
  3. Apr 25, 2015 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Can you think of a conserved quantity that might make this problem easier?

    You may also want to consider velocity expressed in other than Cartesian coordinates (if that isn't giving too much help!).
  4. Apr 25, 2015 #3


    User Avatar

    Staff: Mentor

    @sitzpillow -- You are required to show us your efforts toward the solution before we can offer much tutorial help. Please use the hint provided by PeroK and show us your efforts...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook