Finding Friction's Magnitude

Q.

An object is gently placed on a long conveyer belt moving with a uniform speed of $5m{s}^{-1}$. If the coefficient of friction between the block and the belt is 0.5, how far will the box move on the belt (relative to belt) before coming to rest? Take $g=10m{s}^{-2}$.

1. 2.0 m

2. 2.5 m

3. 3.0 m

4. 3.5 m

Q. A block of mass $3\text{kg}$ is at rest on a rough inclined plane as shown in the figure. The magnitude of net force exerted by the surface on the block will be $(g=10{\text{m/s}}^2)$

1. $26\text{N}$
2. $19.5\text{N}$
3. $10\text{N}$
4. $30\text{N}$

Q. A block is gently placed on a conveyor belt moving horizontally at a constant speed. After $t=4\text{s}$, the velocity of the block becomes equal to the velocity of the belt. If the coefficient of static friction between the block and the belt is $\mu =0.2$, then what is the velocity of the conveyor belt ?

1. $2\text{m/s}$
2. $4\text{m/s}$
3. $6\text{m/s}$
4. $8\text{m/s}$

Q. Two bodies of masses $1kg$ and $2kg$ are projected with same velocities, on two rough surfaces whose coefficients of friction are $0.2$ and $0.4$ respectively. Find the ratio of distances travelled by them before their velocities become half of the initial value.

1. $1:3$
2. $2:1$
3. $1:4$
4. $4:1$

Q. A block placed on a rough inclined plane of inclination $(\theta ={30}^{\circ })$ can just be pushed upwards by applying a force ${}^{\prime }{F}^{\prime }$ as shown. If the angle of inclination of the inclined plane is increased to $(\theta ={60}^{\circ })$, the same block can just be prevented from sliding down by the application of a force of the same magnitude. The coefficient of friction between the block and the inclined plane is

1. $\frac{\sqrt{3}+1}{\sqrt{3}-1}$
2. $\frac{2\sqrt{3}-1}{\sqrt{3}+1}$
3. $\frac{\sqrt{3}-1}{\sqrt{3}+1}$
4. None of these

Q. A force $F=(\hat{i}+4\hat{j})\text{N}$ acts on the block shown. The force of friction acting on the block is :

1. $-\hat{i}\text{N}$
2. $-18\hat{i}\text{N}$
3. $-2.4\hat{i}\text{N}$
4. $-3\hat{i}\text{N}$

Q. A block moving with initial velocity $u=20\text{m/s}$ comes to rest after covering distance of $40m$ on a rough plane. Find out coefficient of kinetic friction. (Take $g=10m/s^2$)

1. $0.5$
2. $0.25$
3. $0.75$
4. Data incomplete

Q.

A block of mass 5 kg is lying on a rough horizontal surface. The coefficients of static and kinetic friction between the block and the surface respectively are 0.7 and 0.5. A horizontal force just sufficient to move the block is applied to it. If the force continues to act even after the block has started moving, what will be the acceleration of the block? Take $g=10m{s}^{-2}$.

1. $1m{s}^{-2}$

2. $2m{s}^{-2}$

3. $3m{s}^{-2}$

4. $4m{s}^{-2}$

Q. For the arrangement shown in the figure, the tension in the string is given by $(sin{37}^{\circ }=\frac{3}{5})$. Take $g=10m{s}^{-2}$

1. $30N$
2. $40N$
   
3. $60N$
4. $30N$

Q. A force $F$ is applied to a block of mass $4\sqrt{3}\text{kg}$ as shown in the diagram. What should be the maximum value of force so that the block does not move?
(Take $g=10{\text{m/s}}^2$)

1. $10\text{N}$
2. $40\text{N}$
3. $80\text{N}$
4. $90\text{N}$

Q. A force $F$ is applied to a block of mass $4\sqrt{3}\text{kg}$ as shown in the diagram. What should be the maximum value of force so that the block does not move?
(Take $g=10{\text{m/s}}^2$)

1. $10\text{N}$
2. $40\text{N}$
3. $80\text{N}$
4. $90\text{N}$

Q.

A block of mass 5 kg is lying on a rough horizontal surface. The coefficients of static and kinetic friction between the block and the surface respectively are 0.7 and 0.5. A horizontal force just sufficient to move the block is applied to it. If the force continues to act even after the block has started moving, what will be the acceleration of the block? Take $g=10m{s}^{-2}$.

1. $1m{s}^{-2}$

2. $2m{s}^{-2}$

3. $3m{s}^{-2}$

4. $4m{s}^{-2}$

Q. A block of mass $3\text{kg}$ is at rest on a rough inclined plane as shown in the figure. The magnitude of net force exerted by the surface on the block will be $(g=10{\text{m/s}}^2)$

1. $26\text{N}$
2. $19.5\text{N}$
3. $10\text{N}$
4. $30\text{N}$