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प्रश्न
Briefly explain ‘rolling friction.'
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उत्तर
The invention of the wheel plays a crucial role in human civilization. One of the important applications is suitcases with rolling on coasters. Rolling wheels makes it easier than carrying luggage. When an object moves on a surface, essentially it is sliding on it. But wheels move on the surface through rolling motion. In rolling motion when a wheel moves on a surface, the point of contact with the surface is always at rest. Since Rolling and kinetic friction, the point of contact is at rest, there is no relative motion between the wheel and surface.
Rolling and kinetic friction
Hence the frictional force is very less. At the same time, if an object moves without a wheel, there is a relative motion between the object and the surface. As a result, the frictional force is larger. This makes it difficult to move the object. The figure shows the difference between rolling and kinetic friction. Ideally in pure rolling, the motion of the point of contact with the surface should be at rest, but in practice, it is not so.
Due to the elastic nature of the surface at the point of contact, there will be some deformation on the object at this point on the wheel or surface as shown in the figure. Due to this deformation, there will be minimal friction between wheel and surface. It is called ‘rolling friction. In fact, rolling friction is much smaller than kinetic friction.
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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 ______
Explain various types of friction.
A heavy uniform chain lies on a horizontal table. If the coefficient of friction between the chain and the table is 0.25, then the maximum fraction of the length of the chain that can hang over one edge of the table 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 slides along a floor while a force of magnitude F is applied to it at an angle θ as shown in figure. The coefficient of kinetic friction is µK. Then, the block's acceleration 'a' is given by ______.
(g is acceleration due to gravity)
A uniform chain of length 3 metres and mass 3 kg overhangs a smooth table with 2 metres laying on the table. If k is the kinetic energy of the chain in joule as it completely slips off the table, then the value of k is ______.
(Take g = 10 m/s2)
A 40 kg wooden crate is being pushed across a wooden floor with a force of 160 N. If µk = 0.3, the acceleration of the crate is ______ m/s2. (g = 10 m/s2}
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)
A chain of mass 'M' and length 'L' is put on a rough horizontal surface and is pulled by constant horizontal force 'F' as shown in the figure. The velocity of the chain as it turns completely ______.
(Coefficient of friction = μ)
