Answer :
Momentum of an object is defined as product of mass and velocity
so it is given as
[tex]P = m* v[/tex]
here it is given that
mass = 0.15 kg
momentum = 6 kg m/s
so by plug in values in the above equation
[tex]6 = 0.15 * v[/tex]
[tex]v = \frac{6}{0.15}[/tex]
[tex]v = 40 m/s[/tex]
so its speed will be 40 m/s