The force of friction between a crate and the floor it is sliding over depends on?

a. the speed the crate is moving over the floor with
b. the surface area of the crate in contact with the floor
c. how much force you are exerting on the crate parallel to the crate's motion
d. how much force the floor is pressing up on the crate with

1 answer

how much force the floor is pressing up on the crate with
F(fr)=μN