Using displacement, velocity and acceleration oscillation equation?

1. Apr 28, 2013

rockchalk1312

1. The problem statement, all variables and given/known data
The function
gives the simple harmonic motion of a body. At t = 1.6 s, what are the (a) displacement, (b) velocity, (c) acceleration, and (d) phase of the motion? Also, what are the (e) frequency (in Hz) and (f) period of the motion?

2. Relevant equations
x(t)=xmcos(ωt+ϕ)
v(t)=-ωxmsin(ωt+ϕ)
a(t)=-ω2xmcos(ωt+ϕ)

3. The attempt at a solution
I'm just trying to get the first problem! How is it incorrect to do 4.5cos(6∏(1.6)+∏/3)=3.84m?

I've tried all different amounts of sigfigs; can someone enlighten me? And I wouldn't hate tips on the rest of the problem besides just a. Thank you!

2. Apr 28, 2013

UVW

You're thinking is perfect on the first part, but remember that the numbers they give you in the cosine function are in radians, not degrees!

For the rest, you've got all the necessary equations, just remember what each term represents!

3. Apr 28, 2013

rockchalk1312

Perfect thank you!