A mass of 100 g stretches a spring 5 cm. If the mass is set in motion from its equilibrium position with a downward velocity of 30 cm/s, and if there is no damping, determine the position u of the mass at any time t. (Use g = 9.8 m/s2 for the acceleration due to gravity. Let u(t), measured positive downward, denote the displacement in meters of the mass from its equilibrium position at time t seconds.)

Respuesta :

Answer:

[tex]u(t)=\frac{15}{7}*sin(14t)[/tex]

Explanation:

Given

[tex]m=100g[/tex]

[tex]L=5cm[/tex]

[tex]u(0)=0[/tex]

[tex]u(0)'=30\frac{cm}{s}[/tex]

The function that describe the motion is:

[tex]u(t)=A*cos(wt)+b*sin(wt)[/tex]

[tex]w_{o}^2=\frac{g}{L}[/tex]

[tex]w_{o}^2=\frac{9.8\frac{m}{s^2}}{0.05m}[/tex]

[tex]w=\sqrt{196\frac{m^2}{s^2}}=14\frac{m}{s}[/tex]

[tex]u(t)=A*cos(14t)+B*sin(14t)[/tex]

[tex]u(0)=0+30=B*sin(14)[/tex]

[tex]14B=30[/tex]

[tex]B=\frac{15}{7}[/tex]

[tex]u(t)=\frac{15}{7}*sin(14t)[/tex]