I. the normal reaction between the surfaces
II. the area of surface in contact
III. the relative velocity between the surfaces
IV. the nature of the surface
A. I only
B. I & IV only
C. II only
D. III only
Correct Answer: Option B
B. I & IV only
Explanation
– Friction depends on the nature of the surfaces in contact
– Solid friction is independent of the area of the surfaces in contact and the relative velocity between the surfaces.