PHYSICS [2 Mark Question Answer]

Rough towelled cloth on the handles of motrbike provides good grip increasing the friction and we have better control in holding the handles.

Streamlined shapes experience minimum drag (fluid friction) while travelling through air and water. Hence, boats and ships are given streamlined shape.

Vehicles slip/skid on muddy and wet roads as the roads become smooth and offer less friction to the tyres. Tyres are therefore grooved or treaded to make their surface rough so that the friction between the tyres and the road increases and vehicles may stop easily when desired.

When we roll an object on a surface, the friction produced between the object and the surface is called rolling friction. Example : when we pull our large suitcases on wheels, rolling friction comes into play. The wheels reduce friction and cut down a lot of effort required to move the suitcase (Rolling friction is less than sliding friction).

It is because when the object is at rest, static friction occurs. The static friction is maximum when the applied force is just short of the force required to start motion between the two bodies in contact. Once the object starts moving, friction (resistance) we feel decreases.

Characteristics of force of friction are :

• Friction opposes the direction of motion.
• It depends on the nature of the surface that are in contact. Rough surfaces offer greater degree of friction as compared to smooth surfaces. More the roughness of a surface, greater is the friction.
• Friction depends upon the weight of the object – greater is the weight of the object, greater is frictional force it faces.
• Friction is independent of area of surface in contact, when the weight remains unchanged.