A 2.7 kg box is released on a horizontal surface with an initial speed of 2.9 m/s. It moves on the surface with an acceleration of .27 m/s squared. Calculate the kinetic friction force on the box. The coefficent of the kinetic force is .156.

Answer 1

The acceleration is negative since the surface is horizontal and friction is the only horizontal force acting.

Compute the friction force from
F = m a

That gives F = 0.73 Newtons

There is another way to compute the friction force, and it gives a different result.
F = (kinetic coefficient) * M g

Your problem is inconsistent and overspecified. The initial speed makes no difference.