Answer
given,
mass = 3 kg
x = 1.50 m
Restoring Force
F = (2.00 N/m)x + (1.00 N/m2)x²
work done = [tex]\int F.dx[/tex]
= [tex]\int( (2.00)x + (1.00)x^2)dx[/tex]
= [tex]x^2 +\dfrac{1}{3}x^3[/tex]
now work done at x = 1.5
= [tex]x^2 +\dfrac{1}{3}x^3[/tex]
= [tex]1.5^2 +\dfrac{1}{3}1.5^3[/tex]
W= 3.375 J
we know
[tex]W = \dfrac{1}{2}mv^2[/tex]
[tex]3.375 = \dfrac{1}{2}\times 3 \times v^2[/tex]
v = 1.5 m/s