Question

Which types of friction is the force between a wheel or roller and the surface which is in contact with? I. Sliding Friction II. Static Friction III. Rolling
A.I
B.II
C.II and III
D III

Answer 1

Answer:

unless the roller is in rest, the friction is STATIC

but when the roller starts to move, the friction is ROLLING.

So, (c) both static and rolling