Particle Motion Problem: Frequency, Period, Amplitude & Phase Constant

[MJay82]

Homework Statement

The position of a particle is given by the expression x=4.00 cos (3.00\pit+\pi) where x is in meters and t is in seconds. Determine the frequency, period of the motion, amplitude of the motion, the phase constant, and the position of the particle at t=0.250 s. **I don't know why this looks like those pi's seem like superscripts - they're not.

Homework Equations

Not sure - probably what my problem is.

The Attempt at a Solution

Alright, I can get the frequency, period, amplitude and phase constant. But what I'm confused about is why I don't just plug .25 s into t in the equation and solve for x to get the position of the particle at t=.25 s, and how to solve the problem correctly. The answer in the book is 2.83 m.

 

[Doc Al]

**I don't know why this looks like those pi's seem like superscripts - they're not.

Use 'inline' Latex tags: 'itex' instead of 'tex': x=4.00 cos (3.00\pit+\pi)

But what I'm confused about is why I don't just plug .25 s into t in the equation and solve for x to get the position of the particle at t=.25 s, and how to solve the problem correctly.

That's all there is to it. Make sure your calculator is in radian mode.

 

[MJay82]

Radians. Gah. Thank you.