Normal Reaction

Q. A block of mass 15 kg is resting on a rough inclined plane as shown in figure. The blocks tied up by a horizontal string which has a tension of S0N. The coefficient of frictionbetween the surface is

Q. A thin cylindrical rod of uniform mass density, rests against a smooth wall as shown in figure. Find the coefficientof friction between ground and rod (if the minimum angle that the rod can make with the horizontal is theta)

Q. 28.The friction coefficient between the table and the block shown in figure is 0.2. The ratio of tension in the two strings T1/T2 is (pulleys and strings are light)

Q.

A hanging body of mass $m_1$ is pulled by a force F = $m_2$ g acting on the massless inextensible smooth string. The acceleration of $m_1$ is:

1. 

2. 

3. 

4. 

Q. (1)16A force F is applied at the topmost point of blockof mass M. The force required to topple the blockbefore sliding is (u coefficient of friction)(3)

Q. A block inclined at an angle of 30 degree and connected with a string and coefficient of friction is 0.7 then find the tension in the string

Q. A 1/nth part of uniform chain of mass M and length L is hanging below the edge of the rough table having coefficient of friction u (meu) .Find the work done in pulling the chain on the table. If suddenly the chain slips then find the velocity of chain while leaving the table.

Q. While walking on ice, one should take small steps to avoid slipping. This is because smaller steps ensure
(a) larger friction
(b) smaller friction
(c) larger normal force
(d) smaller normal force.

Q.

Free body diagram of a car taking turn on the plane road is

1. 

2. 

3. 

4. 

Q. 58. A block is placed on a rough horizontal surface.the minimum force required to slide the block is

Q. 15. Find workdone to pull the chain from point A to point C where point A is one edge of the table and point C is its another edge. The length of chain is L and mass is M. The length L of chain is hanging from point A. The coefficient of friction on table is mu.

Q. A block of mass 2kg is placed on a fixed rough wedge with co efficient of friction =0.7 , angle of the icline is 30 degree .Find tension in the string

Q. a rod of length 2m rests on a smooth horizontal floor. If the rod is heated from 0 degree celsius to 20 degree celsius. Find the longitudinal strain developed?

Q. 53. A block of weight 3N is pushed against a vertical wall by a force 4N.The coefficient of friction between the wall and block is 0.75.The magnitude of force exerted by the wall on the block is.

Q. The normal reaction between the blocks $N_1,N_2$ are

1. $50N,20N$
2. $100N,50N$
3. $50N,200N$
4. $100N,20N$

Q. 120.The vector sum of two forces is perpendicular to their vector differences. In that case, the fores is

Q. A person (40 kg) is managing to be at rest between two vertical walls by pressing one wall A by his hands and feet and the other wall B by his back (figure 6−E11). Assume that the friction coefficient between his body and the walls is 0.8 and that limiting friction acts at all the contacts. (a) Show that the person pushes the two wall with equal force. (b) Find the normal force exerted by either wall on the person. Take g = 10 m/s².

Figure

Q. A block of mass $m$ is kept on the floor of a freely falling lift. During the free fall of the lift, the block is pulled horizontally with a force of $F=5\text{N}.$ If coefficient of friction between block and floor is ${\mu }_s=0.1$, then the frictional force on the block will be

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

Q. A block of mass m moves on a horizontal circle against the wall of a cylindrical room of radius R. The floor of the room on which the block moves is smooth but the friction coefficient between the wall and the block is μ. The block is given an initial speed v₀. As a function of the speed v write (a) the normal force by the wall on the block, (b) the frictional force by wall and (c) the tangential acceleration of the block. (d) Integrate the tangential acceleration $\left(\frac{dv}{dt}=v\frac{dv}{ds}\right)$ to obtain the speed of the block after one revolution.

Q. Q. Two forces, $F_{1}and{F}_2$ are acting on a body. One force is double that of the other the resultant is equal to the greater force. Then the angle between the two forces is
a) ${\cos }^{-1}$ (1/2)
b) ${\cos }^{-1}$ (—1/2)
c) ${\cos }^{-1}$ (—1/4)
d) ${\cos }^{-1}$ (1/4)

Q. A block of mass $m$ is kept on the floor of a freely falling lift. During the free fall of the lift, the block is pulled horizontally with a force of $F=5\text{N}.$ If coefficient of friction between block and floor is ${\mu }_s=0.1$, then the frictional force on the block will be

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

Q. An insect crawls up a hemispherical surface very slowly as shown in the figure. The coefficient of static friction between the insect and the surface is $\frac{1}{3}$. If the line joining the centre of the hemispherical surface to the insect makes an angle $\alpha$ with the vertical, then the maximum possible value of $\alpha$ is given by

1. $\cot \alpha =3$
2. $\tan \alpha =3$
3. $\sec \alpha =3$
4. $\cos \alpha =3$

Q. Why is it difficult to walk on solid ice?

Q. How is frictional force vector non collinear?

Q. A block of mass of $10kg$ is in contact with the inner wall of a hollow cylindrical drum of radius $1m.$ The coefficient of friction between the block and the inner wall of the cylinder is $0.1.$ The minimum angular velocity needed for the cylinder to keep the block stationary when the cylinder is vertical and rotating about its axis, will be $\left(g=10m/s^2\right)$

1. $\sqrt{10}\frac{rad}{s}$
2. $\frac{10}{2\pi }\frac{rad}{s}$
3. $10\frac{rad}{s}$
4. $10\pi \frac{rad}{s}$

Q. A body of mass 10 kg is placed on rough surface, pulled by a force F having an angle 30
degree above the horizontal . If the angle of friction is also 30 degree, then the minimum magnitude of force F required to move the body is equal to (g= 10ms^-2) ?

Q.

what happens to coefficint of friction when weight of body is doubled ?

Q. 22.Five equal forces each of 20N are acting at a point in the same plane.If the angles between them are same, the resultant of these forces is