A 2.00-kg, frictionless block is attached to an ideal spring with force constant 300 N/m. At t=0 the block has velocity -4.00 m/s and displacement +0.200 m.
Find:
(a) the amplitude and (b) the phase angle.
c) Write an equation for the position as a function of time.
Assume x(t) in meters and t in seconds

Respuesta :

Answer:

0.38296 m

1.02132 rad

[tex]x(t)=0.38296cos(12.24744 t+1.02132)[/tex]

Explanation:

Angular frequency is given by

[tex]\omega=\sqrt{\dfrac{k}{m}}\\\Rightarrow \omega=\sqrt{\dfrac{300}{2}}\\\Rightarrow \omega=12.24744\ rad/s[/tex]

Displacement is given by

[tex]x(t)=Acos(\omega t+\psi)\\\Rightarrow 0.2=Acos(12.24744\times 0+\psi)\\\Rightarrow 0.2=Acos\psi\\\Rightarrow A=\dfrac{0.2}{cos\psi}[/tex]

Velocity is given by

[tex]v=-A\omega sin(\omega t+\psi)\\\Rightarrow -4=\dfrac{0.2}{cos\psi}12.24744sin(12.24744\times 0+\psi)\\\Rightarrow 4=\dfrac{1}{cos\psi}2.449488sin(\psi)\\\Rightarrow tan\psi=\dfrac{4}{2.449488}\\\Rightarrow \psi=tan^{-1}\dfrac{4}{2.449488}\\\Rightarrow \psi=1.02132\ rad[/tex]

The phase angle is 1.02132 rad

[tex]A=\dfrac{0.2}{cos\psi}\\\Rightarrow A=\dfrac{0.2}{cos1.02132}\\\Rightarrow A=0.38296\ m[/tex]

The amplitude is 0.38296 m

The equation is given by

[tex]x(t)=Acos(\omega t+\psi)\\\Rightarrow x(t)=0.38296cos(12.24744 t+1.02132)[/tex]

The equation is [tex]x(t)=0.38296cos(12.24744 t+1.02132)[/tex]