Question

Why is friction greatly reduced when a body rolls over a surface?

Answer 1

Answer:

sliding friction is greatly reduced...than rolling friction.the body is contact with the ground.but in rolling friction,the body rolls upon another there is no sliding or slip between them....

Answer 2

Answer:-

Friction gets reduced as rolling friction depends on area of contact of the body.

Note:-

No friction other than rolling friction depends upon area of contact.

While rolling the the area of contact is very less with the other surface(floor) . The friction acting on the rolling body is very less,Thus,it is easier to roll a body on any surface.

Additional information

$rolling \: friction < kinetic \: friction< static \: friction$

• Limiting friction is also called as self adjusting frictional force.
• Static friction only acts when body is about to move.
• Kinetic friction acts when body starts moving.
• Let a box of weight W be displaced by S. by a force F .N is the normal reaction over a surface with co-efficient of friction μ

 

Thus frictional force: f= μW  Work done 

against friction= work done by frictional 

force over the displacement.The 

displacement is in opposite direction to

 that of the fricitional force, Thus 

Work=f.s cos 180= -f.s=-W.

Work=f.s cos 180= -f.s=-W.This implies f=- μW.

The above relation is with respect to sign convention.