Pendulum - find maximum angular displacement

AI Thread Summary
The discussion centers on finding the maximum angular displacement of a pendulum described by the equation theta=0.2cos(8t). The maximum angular displacement is determined by the amplitude of the cosine function, which is 0.2 radians. The user expresses frustration over the lack of endpoints for evaluating the function and considers using graphical methods to visualize the behavior of the cosine function. Additionally, they mention the importance of recalling the values that maximize the cosine function. Ultimately, understanding the properties of the cosine function is key to solving the problem.
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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.
 
Physics news on Phys.org
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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