Q.2 Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements are given below. Choose the correct arrangement.
(a) rolling, static, sliding
(b) rolling, sliding, static
(c) static, sliding, rolling
(d) sliding, static, rolling

Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements will be as follows:-

(c) static, sliding, rolling.

EXPLANATION

In rolling friction, two surfaces never comes in contact for even a little time period as the object gets rolled and continuously changes its surface of contact within a span of seconds. So in rolling friction, the time given for interlocking is almost negligible, and thus there is no interlocking at any point of the time, as a result of which rolling provides very less friction as compared to sliding friction and static friction.

While in case of sliding friction, the time given for interlocking is small as compared to that of static friction but as interlocking takes place for some moments, so the resulting interlocking is not so strong. With the application of less external force, one can overcome this type interlocking. Hence sliding provides less friction as compared to static friction.

In case of static friction, the interlocking between the two surfaces of the two objects is much more stronger than the interlocking provided by the sliding friction. So this type of interlocking requires more external force to overcome the friction created because of this interlocking.