A 5.7 kg block attached to a spring executes simple harmonic motion on a frictionless horizontal surface. At time t = 0s, the block has a displacement of -0.70m, a velocity of -0.80 m/s, and an acceleration of +2.7 m/s2. What is the amplitude of the motion?

Respuesta :

Answer:

Explanation:

Given

mass of block [tex]m=5.7\ kg[/tex]

at [tex]t=0 s[/tex]

displacement is [tex]x=-0.7\ m[/tex]

velocity [tex]v=-0.8\ m/s[/tex]

acceleration [tex]a=2.7\ m/s^2[/tex]

suppose [tex]x=A\cos (\omega t+\phi )[/tex]   is the general equation of SHM

where A=amplitude

[tex]\omega [/tex]=natural frequency of oscillation

therefore velocity and acceleration is given by

[tex]v=-A\omega \sin (\omega t+\phi )[/tex]

[tex]a=A\omega ^2\cos (\omega t+\phi )[/tex]

for t=0

[tex]-0.7=A\cos (\phi )---1[/tex]

[tex]v=-0.8=-A\omega \sin(\phi)---2[/tex]

[tex]a=2.7=-A\omega ^2\cos(\phi )----3[/tex]

divide 1 and 3 we get

[tex]\omega ^2=\frac{27}{7}[/tex]

[tex]\omega =\sqrt{\frac{27}{7}}[/tex]

Now square and 1 and 2 we get

[tex](0.7)^2+(\frac{0.8}{\omega })^2=A^2[/tex]

[tex]A^2=0.49+0.166[/tex]

[tex]A=0.81\ m[/tex]