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प्रश्न
State the empirical laws of static and kinetic friction.
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
Explain various types of friction.
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.
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:
If a body of mass m is moving on a rough horizontal surface of coefficient of kinetic friction µ, the net resultant force exerted by surface on the body is ______.
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 coefficient of static friction between a car's tires and a level road is 0.80. If the car is to be stopped in a maximum time of 3.0 s, its speed cannot exceed.
Starting from rest, a body slides down a 45° inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is ______.
A block of mass 10 kg starts sliding on a surface with an initial velocity of 9.8 ms-1. The coefficient of friction between the surface and bock is 0.5. The distance covered by the block before coming to rest is ______.
[use g = 9.8 ms-2]
