A 12.0-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0m/s. the crate then slides down a frictionless incline and across a second horizontal surface. what is the speed of the crate when it arrives at the lower surface, what is the kinetic energy of the crate as it slides on the lower surface, and what minimum coefficient of kinetic friction is required to bring the crate to a stop over a distance of 8.0m along the lower surface.