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: Pendulum - find maximum angular displacement

  1. Oct 28, 2009 #1
    1. The problem statement, all variables and given/known data
    A 15-centimeter pendulum moves according to the equation:


    where theta is the angular displacement from the vertical in radians and t is the time in seconds. Determine the maximum angular displacement and the rate of change of theta when t=3 seconds.

    2. Relevant equations
    See, here's where I get stuck. It doesn't seem like I'm given enough information to do ANYTHING with this problem. At first I thought I could find the absolute maximum value by solving for theta at the endpoints and critical numbers, but I don't have any endpoints. Any physics equations I could use go out the window as well, because I have no initial displacement or velocity or any such stuff.

    3. The attempt at a solution
    Insert an hour of frustrated grumbling here, with no results.
  2. jcsd
  3. Oct 28, 2009 #2


    User Avatar
    Homework Helper

    Graph y=0.2cos8t to see the whole picture!
    Or recall what value(s) of x make cos x a maximum. Graph y = cos x if you don't recall.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook