A force of 9 pounds stretches a spring 1 foot. A mass weighing 6.4 pounds is attached to the spring, and the system is then immersed in a medium that offers a damping force numerically equal to 1.2 times the instantaneous velocity. Find the equation of motion If the mass is initially released from rest from a point 1 foot above the equilibrium position.

Respuesta :

Answer:

[tex]\frac{d^2x}{dt^2}+\frac{\beta}{m}\frac{dx}{dt}+\frac{k}{m}x=0[/tex]

Explanation:

let [tex]m[/tex] be the mass attached, let [tex]k[/tex] be the spring constant and let [tex]\beta[/tex] be the positive damping constant.

-By Newton's second law:

[tex]m\frac{d^2x}{dt^2}=-kx-\beta \frac{dx}{dt}[/tex]

where [tex]x(t)[/tex] is the displacement from equilibrium position. The equation can be transformed into:

[tex]\frac{d^2x}{dt^2}+\frac{\beta}{m}\frac{dx}{dt}+\frac{k}{m}x=0[/tex]  shich is the equation of motion.