Friction: Bottom Most Point

Q.

What is the condition for pure rolling?

Q. A rigid body of mass $m$ and radius $R$ rolls without slipping on a rough surface. A force is acting on the rigid body at distance $x$ from the centre as shown in figure. Find the value of $x$ so that static friction will be zero.

1. $\frac{I_{\text{cm}}}{2mR}$
2. $\frac{2I_{\text{cm}}}{mR}$
3. $\frac{I_{\text{cm}}}{mR}$
4. $\frac{2I_{\text{cm}}}{3mR}$

Q. A rigid body of mass $m$ and radius $R$ rolls without slipping on a rough surface. A force is acting on the rigid body at distance $x$ from the centre as shown in figure. Find the value of $x$ so that static friction will be zero.

1. $\frac{I_{\text{cm}}}{2mR}$
2. $\frac{2I_{\text{cm}}}{mR}$
3. $\frac{I_{\text{cm}}}{mR}$
4. $\frac{2I_{\text{cm}}}{3mR}$

Q. A round shaped body is released on an inclined plane. Friction is sufficient for pure rolling, mass of body is m & it is released from a height "h". Then which of the following is correct?

1. Work done by friction is negative
2. At bottom total weight is less than mgh
3. Total K.E. on the ground is mgh & ratio of $K{E}_{trans}$ & $K{E}_{rotative}$ depends upon shape of the body
4. None of the above

Q. When a body rolls without sliding, up an inclined plane, the frictional force is

1. Directed up the plane
2. Directed down the plane
3. Zero
4. Dependent on its velocity

Q. A body of mass $m$ and radius $R$ is rotating with angular velocity $\omega$ as shown in figure and kept on a surface that has sufficient friction. Then, the body will move:

1. initially in backward direction, then along forward direction
2. initially in forward direction, then along backward direction
3. will always move along forward direction.
4. none of these

Q. As shown in figure, a uniform disc of mass $m$ is rolling without slipping with an angular velocity $\omega$. The portion $AB$ is rough and $BC$ is smooth. If the disc crosses point $B$, the motion of the disc will be:

1. translational motion only
2. pure rolling motion
3. rotational motion only
4. none of these

Q. A body of mass $m$ and radius $R$ is rotating with angular velocity $\omega$ as shown in figure and kept on a surface that has sufficient friction. Then, the body will move:

1. initially in backward direction, then along forward direction
2. initially in forward direction, then along backward direction
3. will always move along forward direction.
4. none of these