Answer
$E=37mJ$
Work Step by Step
Mechanical energy is the sum of kinetic and potential energy.
Mathematically
$E=K.E+P.E$
$E=\frac{1}{2}mv^2+\frac{1}{2}Kx^2$
in this case $x=A(amplitude)$and $v=0$ at amplitude
so
$E=\frac{1}{2}m(0)^2+\frac{1}{2}KA^2$
$E=\frac{1}{2}KA^2$
putting the values
$E=\frac{1}{2}(1.3)(2.4)^2$
$E=3.744N.cm$
$E=\frac{3.744}{100}N.m$
$E=0.03744N.m$
$E=0.03744J$
$E=37.44\times10^{-3}J$
After rounded it off and replacing$10^{-3}=mili$,we get
$E=37mJ$
