How do you find force of friction from applied force and velocity?

If the object is moving at a constant speed, then according to Newton's 1st Law, it must be in equillibrium. (total forward force = total backward force).

Assuming that
1. there are no other resistive forces than friction (such as air resistance),

2. that the 5N force is acting in the direction that the object is moving (ie parallel to the floor),

3. and that the object is modelled as a particle so that there are no (unbalanced) moments about the object, (doesn't tend to topple),

then since the total forward force = total backward force, the force of friction must also be 5N for it to travel in a constant velocity, irrespective of its mass.

Since the object is not accelerating, the sum of the forces must equal 0 N.
Friction force + 5 N = 0
Friction force = -5 N
The negative sign means the friction force is in the opposite direction of the applied force.

Friction force = µ * mass * g
µ * 60 * 9.8 = 5