NCERT Solutions for Chapter: Friction, Exercise 3: SHORT ANSWER QUESTIONS

You might have noticed that when used for a long time, slippers with rubber soles become slippery. Explain the reason.
 

Is there a force of friction between the wheels of a moving train and iron rails? If yes, name the type of friction. If an air cushion can be introduced between the wheel and the rail, what effect will it have on the friction?
 

Cartilage is present in the joints of our body, which helps in their smooth movement. With advancing age, this cartilage wears off. How would this affect the movement of joints?
 

While playing tug of war (Figure), Preeti felt that the rope was slipping through her hands. Suggest a way out for her to prevent this.

The handle of a cricket bat or a badminton racquet is usually rough. Explain the reason.
 

Explain why the surface of mortar and pestle (silbatta) used for grinding is etched again after prolonged use?

A marble is allowed to roll down an inclined plane from a fixed height. At the foot of the inclined plane, it moves on a horizontal surface
(a) covered with silk cloth
(b) covered with a layer of sand and
(c) covered with a glass sheet.
On which surface will the marble move the shortest distance. Give reason for your answer.

A father and son pushed their car to bring it to the side of road as it had stalled in the middle of the road. They experienced that although they had to push with all their might initially to move the car, the push required to keep the car rolling was smaller, once the car started rolling. Explain.