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प्रश्न
State the empirical laws of static and kinetic friction.
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उत्तर
The empirical laws of friction are:
- Friction is independent of the surface of contact.
- The coefficient of kinetic friction is less than the coefficient of static friction.
- The direction of frictional force is always opposite to the motion of one body over the other.
- Frictional force always acts on the object parallel to the surface on which the object is placed,
- The magnitude of frictional force between any two bodies in contact is directly proportional to the normal reaction between them.
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संबंधित प्रश्न
An object of mass m begins to move on the plane inclined at an angle θ. The coefficient of static friction of inclined surfaces is µs. The maximum static friction experienced by the mass is ______
A long stick rests on the surface. A person standing 10 m away from the stick. With what minimum speed an object of mass 0.5 kg should he has thrown so that it hits the stick. (Assume the coefficient of kinetic friction is 0.7).
People often say “For every action, there is an equivalent opposite reaction”. Here they meant ‘action of a human’. Is it correct to apply Newton’s third law to human actions? What is mean by ‘action’ in Newton's third law? Give your arguments based on Newton’s laws.
Briefly explain ‘rolling friction.'
A uniform metal chain is placed on a rough table such that one end of the chain hangs down over the edge of the table. When two-thirds of its chain length hangs over the edge the chain start sliding. Then the coefficient of static friction is:
A block of mass 20 kg is sliding on a surface is inclined at an angle of 45° with the horizontal. What will be the acceleration of the block if the coefficient of kinetic friction between the block and the surface is 0.7?
A block of mass m is pulled by a constant power P placed on a rough horizontal plane. The friction co-efficient between the block and the surface is µ. Maximum velocity of the block will be:
A block of mass m = 1 kg moving on horizontal surface with speed u = 2 m/s enters a rough horizontal patch ranging from x = 0.10 m to x = 2.00 m. If the retarding force fr on the block in this range is inversely proportional to x over this range i.e.
fr = `"-k"/x` 0.10 < x < 2.00
= 0 for x < 0.10 and x > 2.00
If k = 0.5 J then the speed of this block as it crosses the patch is (use ℓn 20 = 3)
The minimum radius of a circle along which a cyclist can ride with a velocity 18 km/hr if the coefficient of friction between the tyres and the road is µ = 0.5, is ______ (Take g = 10 m/s2)
Block A has a mass of 2 kg and block B has 20 kg. If the coefficient of kinetic friction between block B and the horizontal surface is 0.1, and B is accelerating towards the right with a = 2 m/s2, then the mass of the block C will be ______.
(g = 10 m/s2)
