Question

Find the first time after release that the string is 70 cm

Answer 1

Given: A function representing the length of the string after t seconds-

`L=80+30cos(\pi t)`

Required: To determine the first time after release that the string is 70 cm.

Explanation: The given function is-

`L=80+30cos(\pi t)`

Substituting L=70 as follows-

`70=80+30cos(\pi t)`

Further solving for t as-

`\begin{gathered} cos(\pi t)=-(1)/(3) \\ \pi t=cos^(-1)(-(1)/(3)) \\ t=(1.91063)/(\pi) \end{gathered}`

Substituting the value of pie and solving gives-

`t=0.6084\text{ seconds}`