Here, `k=1200Nm^(-1),m=3.0kg,`

`y=1.0cm =0.01m,`

`a=2.0cm=0.02m`

(a) Speed, `V=omegasqrt(a^(2)-y^(2))`

`=sqrt((k)/(m))(a^(2)-y^(2))^(1//2)`

`sqrt((1200)/(3))[(0.02)^(2)-(0.01)^(2)]^(1//2)`

`=0.346ms^(-1)`

(b) The body is momentarily at rest, when `y=a`

`P.E. =(1)/(2)ka^(2)=(1)/(2)xx1200xx(0.02)^(2)=0.24J`

(c) Total energy `=` P.E. `+` K.E.

`=0.24+0=0.24J`