A body of mass \(m\) is slipping on a rough horizontal plane, decelerating at \(6\) m/s2. The net force exerted by the plane on the body is: (take \(g =10~\text{m/s}^{2}\))
1. \(1.6~mg\)
2. \(0.4~mg\)
3. \(\sqrt{1.36}~mg\)
4. \(\sqrt{1.16}~mg\)

Subtopic:  Friction |
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A horizontal force \(F_{\text{ext}}\) is applied to a block of mass \(m,\) on a fixed incline, as shown in the figure. The coefficient of friction between the block and the incline is \(\mu.\) The normal reaction of the incline on the block is \(N\) and the acceleration of the block, up the incline, is \(a.\) The values of \(F_{\text{ext}}\) & \(\mu\) are given in Column-I, while the values of \(N\) & \(a\) are given in Column-II. Match the values in Column-I with the corresponding ones in Column-II.
Column-I Column-II
\(\mathrm{(A)}\) \(F_{\text{ext}}=mg,\mu=0\) \(\mathrm{(I)}\) \(a=g\sqrt2,N=\dfrac{5mg}{\sqrt2}\)
\(\mathrm{(B)}\) \(F_{\text{ext}}=mg,\mu=\dfrac12\) \(\mathrm{(II)}\) \(a=\dfrac{3g}{\sqrt2},N=\dfrac{5mg}{\sqrt2}\)
\(\mathrm{(C)}\) \(F_{\text{ext}}=4mg,\mu=0\) \(\mathrm{(III)}\) \(a=\dfrac{g}{\sqrt2},N=\sqrt2mg\)
\(\mathrm{(D)}\) \(F_{\text{ext}}=4mg,\mu=\dfrac15\) \(\mathrm{(IV)}\) \(a=0,N=\sqrt2mg\)
 
1. \(\mathrm{A\text-IV,B\text-III,C\text-I,D\text-II}\)
2. \(\mathrm{A\text-IV,B\text-IV,C\text-II,D\text-I}\)
3. \(\mathrm{A\text-III,B\text-IV,C\text-II,D\text-I}\)
4. \(\mathrm{A\text-III,B\text-III,C\text-I,D\text-II}\)
Subtopic:  Friction |
 54%

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A \(3\) kg-block is pressed against a vertical wall with a coefficient of friction, \(\mu = \dfrac{3}{4}\). What minimum force should be applied to the block in order to prevent it from falling down?    Take \(g = 10 ~\text{m/s}^2\) 
1. \(\dfrac{3}{4} \times 30 ~\text{N}\) 2. \(\dfrac{4}{3} \times 30 ~\text{N}\)
3. \(\dfrac{3}{5} \times 30 ~\text{N}\) 4. \(\dfrac{4}{5} \times 30~\text{N}\)
Subtopic:  Friction |
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The two blocks \(A,~B\) are connected by an inextensible string, and are lying on a horizontal surface. The blocks move under the action of forces of magnitudes \(F_1\) and \(F_2,\) as shown in the figure. The surface exerts non-zero frictional forces \(f_A,~f_B\) (towards right).

Consider the following situations:
(P) \(f_A,~f_B>0\) (Q) \(f_A,~f_B<0\)
(R) \(f_A>0,~ f_B<0\) (S) \(f_A<0,~ f_B>0\)

Which of the above, are possible? Assume that the string is taut.
1. (P) or (Q)
2. (R) or (S)
3. Any of (P), (Q), (R), (S)
4. Only (P)
Subtopic:  Friction |
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A block of mass \(m\) is placed on a flat horizontal surface, and the coefficient of friction between the block and the surface is \(\mu\). A force \(F_A\) is applied to the block from above, and a force \(F_R\) is applied to the right. In all situations being considered below, the block remains at rest. Let \(f\) be the force of friction on the block.
               
Consider the statements:
(P) \(f\) increases if \(m\) is increased.
(Q) \(f\) increases if \(F_A\) is increased.
(R) \(f\) increases if \(F_R\) is increased.
1. Only P is True.
2. Only Q is True.
3. P, Q are True.
4. Only R is True.
Subtopic:  Friction |
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A block of height \(h\) and width \(w\) is placed on a horizontal table. A horizontal force \(F\) is applied parallel to the top surface of the block. The block does not slip due to friction. Let the frictional force on the block be \(f\) and the normal reaction of the table on the block be \(N.\) Then,
                     
1. \(N\) increases as \(F\) increases.
2. \(N\) does not act through the center of the block.
3. \(f\) is greater than \(F.\)
4. \(f\) acts through the centre of the block.
Subtopic:  Friction |
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The block \(A\) (mass: \(2\) kg) is placed on top of the block \(B\) (mass: \(1\) kg) and the combination is placed on a smooth horizontal table. The coefficient friction between \(A,B\) is \(\mu=0.2.\) What is the maximum horizontal force that can be applied to \(B\) so that the two blocks move together? (Take \(g=10\) m/s2)
                 

1. \(8\) N
2. \(6\) N
3. \(4\) N
4. \(2\) N
Subtopic:  Friction |
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\(2\) kg brick is placed on the ground as shown and it is symmetrically cut into two equal pieces by a plane \(AB,\) which is at \(45^{\circ}\) with the horizontal. The system remains at rest. The force of friction on the upper piece due to the lower is: (Take \(g\)\(10\) m/s2)
                      
1. \(10\) N
2. \(10 \sqrt 2\)  N
3. \(5 \sqrt 2\) N
4. \(5\) N
Subtopic:  Friction |
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A block of mass \(5\) kg requires a minimum horizontal force of \(20\) N to cause it to move. Take \(g=10\) m/s2. Let \(\mu_s\) be the coefficient of static friction, and \(\mu\small{_ k}\) be that of kinetic friction.
             
1. \(\mu_s=0.4\)
2. \(\mu_s=\mu{\small_k}=0.4\)
3. \(\mu{\small_ k}=0.4\)
4. \(\mu_s\geq0.4\)
Subtopic:  Friction |
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Two bodies \(A,B\) having masses of \(1\) kg, \(2\) kg respectively are slid on a horizontal surface \((\mu=0.2)\) with the same initial speed \(5\) m/s. If they come to a stop after sliding distances of \(S_A,S_B\) then:
1. \(S_A=2S_B\)
2. \(S_B=2S_A\)
3. \(4S_A=S_B\)
4. \(S_A=S_B\)
Subtopic:  Friction |
 70%
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