A 1.39-kg block slides across a rough surface such that it slows down with an acceleration of 1.43 m/s2. What is the coefficient of kinetic friction between the block and the surface?

Answer 1

Calculate the friction force Ff = m*a

The coefficient of kinetic friction is

Uk = Ff/(m*g) = a/g = ___

You don't need to know the mass.