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Pendulum - find maximum angular displacement

  • Thread starter Lunadora
  • Start date
  • #1
5
0

Homework Statement


A 15-centimeter pendulum moves according to the equation:

theta=0.2cos8t

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.


Homework 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.


The Attempt at a Solution


Insert an hour of frustrated grumbling here, with no results.
 

Answers and Replies

  • #2
Delphi51
Homework Helper
3,407
10
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.
 

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