Question

Which of the following is correct?

I. Sliding friction is smaller than static friction.

II. Rolling friction is smaller than sliding friction.

1.  Neither I nor II 
2.  I and II Both 
3.  Only II
4.  Only I

Answer 1

Correct Answer - Option 2 :  I and II Both 

The correct answer is  I and II Both.

• The opposing forces that are experienced by objects when moving against each other are termed as friction.
• Static friction, sliding friction, and rolling friction are the resistances experienced by stationary, moving, and rolling objects respectively.
• During sliding, contact points do not get enough time to get interlocked properly. Therefore, less friction.
  • But, when the object is at rest, the surfaces interlock well, therefore friction is more. Due to this sliding friction is less than static friction. Hence, Statement 1 is correct.
• The force of friction that appears between two sliding surfaces which are in contact is called sliding friction. The area of contact is less in the case of rolling than in the case of sliding, therefore rolling friction is less than the sliding friction. Hence, Statement 2 is also correct.
• Rolling friction is the resistance to motion experienced by a body when it rolls upon another. It is much less than sliding friction for the same pair of bodies.

• Static friction keeps an object stationary, so it is the maximum.
• Rolling friction, on the other hand, provides the least resistance as the contact time and contact area between the two surfaces is the least.
• Therefore, static friction is the strongest form of frictional force followed by sliding friction which is weaker than static but stronger than rolling friction.