Tag: friction

The force of friction f is always opposite the direction the object that is moving . If the object would move, then the direction of the force of friction f will be opposite the movement. If the object would not move when there is no friction, then the force of friction is zero.Hence, though the surfaces of the object are rough the force of friction can be zero if the object would not move.

Answer is B.

The surface well powdered to stay away from harm to board surface due to scratch.It reduces the friction and helps in smoothing of the board and thereby allows the carom coins to go through in that flow which helps in fast play.
Powder is used in carom board for decreasing friction.

Friction depends upon mass and nature of the body of surfaces.
Friction depends partly on the smoothness of the contacting surfaces, a greater force being needed to move two surfaces past one another if they are rough than if they are smooth. However, friction decreases with smoothness only to a degree; friction actually increases between two extremely smooth surfaces because of increased attractive electrostatic forces between their atoms. 
Friction does not depend on the amount of surface area in contact between the moving bodies or (within certain limits) on the relative speed of the bodies. It does, however, depend on the magnitude of the forces holding the bodies together. 
When a body is moving over a horizontal surface, it presses down against the surface with a force equal to its weight, i.e., to the pull of gravity upon it; an increase in the weight of the body causes an increase in the amount of resistance offered to the relative motion of all the surfaces in contact.

Graphite is the only non-metal element that is a good conductor of electricity. Crystal structures rarely occur and easily break down. This is the reason for the material's greasy feeling despite being a dry lubricant.

However smooth or polished a surface might be, it always has some irregularities. Thus, the friction can never be eliminated.

Oils, grease, graphite, etc., are examples of lubricants. These form a thin layer between the two surfaces in contact thus avoiding them from scrubbing directly against each other. This makes the movement smooth and reduces friction.

If the tyres of automobiles were smooth, the friction produced would be minimal and thus, it would be difficult to stop or turn the automobile, increasing the risk of accidents. Hence, the tyres are grooved so as to increase the friction between the tyre and the surface of the road.

By rubbing their hands with soil, they make their hands rough. A rough surface has more friction which enhances their grip while holding the opponent.

Polishing rough surfaces makes it smooth, thus reducing friction. 

The brake pads press on the wheels and increase the friction since the surface of the brake pads and the wheels are irregular, and the rough surface increases friction that opposes the motion of the wheel.