Final answer:
The coefficient of friction between the block and the rough surface is 0.75.
Step-by-step explanation:
The acceleration of an object sliding on a rough surface can be determined using the equation:
a = (μk * g) - (a * g)
Where a is the acceleration of the object, μk is the coefficient of friction, and g is the acceleration due to gravity.
In this case, the acceleration is given as 1/2 g, so the equation becomes:
1/2 g = (μk * g) - (1/2 g)
Simplifying the equation, we find that the coefficient of friction, μk, is 3/4 or 0.75.