If F applied is 17 Newtons to the right, what is the magnitude and direction of the friction force, if the object is traveling with the constant velocity? Find friction force and its direction

There's some missing context here, but I would guess you're talking about a box or something with some mass m being pushed over a flat surface. Since it's moving with constant velocity, there is no acceleration and so the box is in equilibrium. In particular, the horizontal forces cancel each other. If f is the magnitude of the friction force, then

17 N + (-f ) = 0

f = 17 N

and this force points opposite the direction of motion.

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.