Question

Give reason for your answer.
12.What kind of friction comes into play:
(a) When a block of wood kept on table moves slowly.
(b) When a block of wood kept on table just tends to move (or slip)
(c) When a block of wood kept on cylindrical iron rods moves.
Pls give reason for it

Answer 1

a) When the block moves horizontally, there is kinetic (dynamic) friction that comes into play.

b) When a block of wood kept on table just tends to move or slip,  from initial rest position, then static friction comes into play.  This friction is more than dynamic friction.

c) A block is kept on a set of cylindrical rods.  The rods rotate and so the block moves horizontally.  Then rolling friction comes into play.  This kind of friction is less than the other two types.

Answer 2

a sliding friction

b static friction

c rolling friction