- #1

PhizKid

- 477

- 1

## Homework Statement

A simple pendulum has a ball at the end of mass 5 kg and the length of the string is 5 m. Given [itex]\theta = 0.0800 \cdot cos[4.43t + \phi][/itex] find the maximum velocity

## Homework Equations

[itex]\frac{1}{2}mv^2 = \frac{1}{2}kA^2[/itex]

## The Attempt at a Solution

[itex]\frac{1}{2}mv^2 = \frac{1}{2}kA^2 \\\\

mv^2 = kA^2 \\\\

v = \sqrt{\frac{kA^2}{m}} \\\\

v = \omega \cdot A[/itex]

But the solution is [itex]v = \omega \cdot Length \cdot A[/itex]. Why is it omega * the length * the amplitude?

EDIT: My friend helped me solve it:

w = dtheta / dt = -4.43*.08*sin(4.43t + phi)

w_max => 4.43t + phi = 3pi/2 => w_max = 4.43*.08

v_max = 4.43*.08*R = 5*4.43*.08

Last edited: