If the coefficient of kinetic friction between a 30 kg crate and the floor is 0.35, what horizontal force is required to move the crate at a steady speed across the floor? wHAT HORIZONTAL FORCE IS REQUIRED IF MUK IS ZERO?

If there is no friction, zero firce is required.

With a friction force of M*g*muk = 103 N, and equal force in the direction of motion is required to maingtain constant speed.