Question

Q.1 Static friction is less than (a) sliding friction (b) rolling friction (c) both (a) and (b) (d) None of these


Q.2 If we apply oil on door hinges, the friction will (a) increase (b) decrease (c) disappear altogether (d) will remain unchanged


Q.3 Which of the following is responsible for wearing out of bicycle tires? (a) Muscular force (b) Magnetic force (c) Frictional force (d) Electrostatic force​

Answer 1

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Q.1 Static friction is less than

(a) sliding✔✔

Q.2 If we apply oil on door hinges, the friction will

(b) decrease✔✔

Q.3 Which of the following is responsible for wearing out of bicycle tires?

(b) Magnetic force✔✔

Answer 2

The three answers are provided below:

Q.1 Static friction is less than (d) None of these  

If an object slides on the surface, then the friction experienced is sliding friction and if the object rolls on the surface, the friction observed is rolling friction.

The friction when the object is at rest is called static friction.  

The roughness of the object will form interlocking with the surface if the object is at rest.  But if the object is in motion, the interlocking will not happen properly, hence the value of friction will be less.

Thus, static friction is more than rolling and sliding friction.

Q.2 If we apply oil on door hinges, the friction will (b) decrease

Oil is a lubricant and it makes the surface smooth. This will reduce the frictional force.

Q.3 (c) Frictional force is responsible for wearing out of bicycle tires.

As the bicycle tire is in contact with the ground surface, a frictional force between the ground and the tire opposes its motion.

This results in wearing out of bicycle tires.