Chapter 13 - Oscillations About Equilibrium - Problems and Conceptual Exercises - Page 446: 15

a) $x=(3.50nm)cos(4\pi \times 10^4rad/s)t$ b) sine function

(a) We know that $\omega=2\pi f $ $\implies \omega=2\pi(2.00\times 10^4Hz)$ $\omega=4.0\pi \times 10^4rad/s$ Now $x=Acos(\omega t)$ We plug in the known values to obtain: $x=(3.50nm)cos(4\pi \times 10^4rad/s)t$ (b) We know that $x=Asin(\omega t)$ $\implies x=Asin(0)$ $\implies x=0$f