A 60kg block rests on rough horizontal ground. A rope is
attached to the block and is pulled with a force of 220N to the
left. As a result, the block accelerates at 3 m/s2. The coefficient
of kinetic friction Hk between the block and the ground is
(round to the nearest hundredth)

The coefficient of kinetic friction is

Explanation:

Let us call the force of friction, then we know that is what has caused the acceleration :

Now this frictional force relates to the coefficient of kinetic friction by  

where is the normal force.

Putting in numbers and solving for we get:

Hence, the coefficient of kinetic friction is 0.07.

force tends to be low and long diustance masses are high