Using displacement, velocity and acceleration oscillation equation?

[rockchalk1312]

Homework Statement

The function
x = (4.5 m) cos[(6∏ rad/s)t + ∏/3 rad]
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?

Homework Equations

x(t)=x_mcos(ωt+ϕ)
v(t)=-ωx_msin(ωt+ϕ)
a(t)=-ω²x_mcos(ωt+ϕ)

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!

 

[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!

 

[rockchalk1312]

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!

Perfect thank you!