Net Contact Force

Q.

A force of $1N$ acts on a body of mass of $10kg$. As a result, the body covers $100cm$ in $4seconds$ moving along a straight line. Find the initial velocity.

Q.

A block of mass $2\mathrm{Kg}$ rests on a horizontal surface. If a horizontal force of $5\mathrm{N}$ is applied on the block, the frictional force on it is ( take, ${\mathrm{\mu }}_{\mathrm{k}}=0.4$, ${\mathrm{\mu }}_{\mathrm{s}}=0.5$ )

1. $5\mathrm{N}$

2. $10\mathrm{N}$

3. $8\mathrm{N}$

4. $\mathrm{Zero}$

Q. A block of mass $m$ is at rest with respect to a rough inclined plane kept in an elevator moving up with an acceleration $‘a^{\prime }$. Which of the following statements is correct?

1. $\text{The contact force between block and the inclined plane is parallel to the incline.}$
2. $\text{The contact force between block and the inclined plane is of magnitude}m(g+a)$
3. $\text{The contact force between block and the inclined plane is perpendicular to the incline}$
4. $\text{The contact force between block and the inclined plane is of magnitude}mg\cos \theta$

Q. A body of mass $20kg$ is kept on a rough horizontal surface. If ${\mu }_s=0.5$ and an external force of $F=50N$ is applied on the body, find the contact force on the body. (Take $g=10m/s^2$)

1. $\text{Zero}$
2. $50\sqrt{17}N$
3. $100\sqrt{5}N$
4. $200N$

Q. A force is acting on a body of mass $3kg$ kept on a rough horizontal surface. If a friction force of $40N$ is required to keep the body at rest under the action of this external force. Find the contact force acting on the body. (Take $g=10m/s^2$)

1. $30N$
2. $40N$
3. $50N$
4. $100N$

Q.

A body of mass M is kept on a rough horizontal surface (friction coefficient = $\mu$). A person is trying to pull the body by applying a horizontal force but the body is not moving. The force by the surface on the body is F, where

1. F = Mg

2. F = $\mu$Mg

3. Mg $\le$ F $\le$ Mg $\sqrt{1+{\mu }^2}$

4. Mg $\ge$ F $\ge$ Mg $\sqrt{1+{\mu }^2}$

Q. A force is acting on a body of mass $3\text{kg}$ kept on a rough horizontal surface. If a friction force of $40\text{N}$ is required to keep the body at rest under the action of this external force. Then find the contact force acting on the body. $(g=10{\text{m/s}}^2)$

1. $30\text{N}$
2. $40\text{N}$
3. $50\text{N}$
4. $100\text{N}$

Q. A force is acting on a body of mass $3kg$ kept on a rough horizontal surface. If a friction force of $40N$ is required to keep the body at rest under the action of this external force. Find the contact force acting on the body. (Take $g=10m/s^2$)

1. $30N$
2. $40N$
3. $50N$
4. $100N$

Q. A body of mass $2kg$ is kept on a rough horizontal surface. If ${\mu }_s=0.5$, find the contact force between the body and the surface. Take $g=10m/s^2$.

1. $\text{Zero}$
2. $10N$
3. $10\sqrt{5}N$
4. $20N$

Q. A scooter starting from rest moves with constant acceleration for time $\Delta t_1$ , then with a constant velocity for time $\Delta t_2$ and finally with constant deceleration for time $\Delta t_3$ to come to rest. A man of weight of $600\text{N}$ sitting behind the driver manages to be at rest with respect to the scooter without touching any other part. The force exerted by the seat on the man is

1. $600\text{N}$ throughout the journey.
2. less than $600\text{N}$ throughout the journey.
3. more than $600\text{N}$ throughout the journey.
4. $>600\text{N}$ for a times $\Delta t_1$ and $\Delta t_3$ and $=600\text{N}$ for $\Delta t_2$

Q. A block of mass $2\text{kg}$ rests on a rough inclined plane making an angle of ${30}^{\circ }$ with the horizontal. The coefficient of static friction between the block and the plane is $0.7$. The frictional force on the block is

1. $9.8\text{N}$
2. $0.7\times 9.8\times \sqrt{3}\text{N}$
3. $9.8\times \sqrt{3}\text{N}$
4. $0.7\times 9.8\text{N}$

Q. A scooter starting from rest moves with constant acceleration for time $\Delta t_1$ , then with a constant velocity for time $\Delta t_2$ and finally with constant deceleration for time $\Delta t_3$ to come to rest. A man of weight of $600\text{N}$ sitting behind the driver manages to be at rest with respect to the scooter without touching any other part. The force exerted by the seat on the man is

1. $600\text{N}$ throughout the journey.
2. less than $600\text{N}$ throughout the journey.
3. more than $600\text{N}$ throughout the journey.
4. $>600\text{N}$ for a times $\Delta t_1$ and $\Delta t_3$ and $=600\text{N}$ for $\Delta t_2$

Q. Block is pushed from bottom of inclined plane with speed 6 m/s as shown in figure, find time after which the block will return to the initial position?

1. t=4.2 s
2. t=3.6s
3. t=12.8 s
4. Block will not return

Q.

A body of mass 400g slides on a rough horizontal surface. If the frictional force is 3.0 N, find (a) the angle made by the contact force on the body with the vertical and (b) the magnitude of the contact force. Take g = 10$\frac{m}{s^2}$

1. ${37}^{\circ }$, 5N

2. ${37}^{\circ }$, 4N

3. ${53}^{\circ }$, 4N

4. ${53}^{\circ }$, 5N