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When the surfaces in contact are made to...

When the surfaces in contact are made too smooth by polishing, force of friction.

A

decreases

B

increases

C

becomes zero

D

becomes infinite

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The correct Answer is:
b
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Choose the correct statements – (1) Force of friction is partically independent of microscopic area of surface in contact and relative velocity between them. (if it is not high) (2) Normally with increase in smoothness friction decreases. But if the surface area are made too smooth by polishing and cleaning the bonding force of adhesion will increase and so the friction will increase resulting in 'Cold welding' (3) Friction is a non conservative force, i.e. work done against friction is path dependent. (4) Force of fricton depends on area

Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play

The friction that exists between the surface of two bodies in contact when one body is sliding over the other is called "_____".

Why is the surface of a slide polished to make it smooth ?

Friction between any two surfaces in contact is the force that opposes the relative motion between them The force of limiting friction (F) between any two surfaces in contact is directly proportional to the normal reaction (R) between them F prop R or F = mu R where mu is coefficient of limiting friction If theta is angle of friction then mu = tan theta A force of 49N is just able to move a block of wood weighing 10kg on a rough horizontal surface The coefficient of friction is .

Why frictional force gets increased when two surfaces in contact are polished beyond a certain limit ?

A block is sliding on a rough horizontal surface. If the contact force on the block is sqrt2 times the frictional force, the coefficient of friction is

Assertion : Force of friction depends on the actual area of contact Reason : Smoother the surfaces of contact smaller is opposition to motion .

PRADEEP-LAWS OF MOTION-Multiple Choice Questions
  1. In Ques 1 the force of dynamic friction is.

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  2. Which of the following is a self adjusting force ?

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  4. Angle of repose for a rough inclined plan is 60^(@) The coefficient of...

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  5. In moving a body of mass m once up and down a smooth incline theta tot...

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  6. In moving a body of mass m once up and down a smooth incline 0 total w...

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  9. A ball is travelling with uniform translatory motion. This means that

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  10. A metre scale is moving with uniform velocity. This implies .

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  15. A body of mass 2kg travels according to the law x (t) = pt + qt^(2) + ...

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  16. A body with mass 5 kg is acted upon by a force vec(F) = (- 3 hat (i) +...

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  18. The motion of a particle of mass m is given by x=0 for tlt0s,x(t)=Asin...

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  19. In the co-efficinet of friction between the floor and the body B is 0....

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  20. Mass m(1) moves on a slope making an angle theta with the horizontal a...

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