Friction

Q.

What happens if there is no friction?

Q. A 40 kg boy sits at 1.2 m from the fulcrum of the see-saw. Where should another boy of 30 kg sit on the other side of the see-saw in order to balance it? (2 marks)

Q.

What will happen if we don’t reduce friction from machines?

Q. A block is at rest on a rough horizontal surface. There is no horizontal force on it. The weight of the block is 5 N. The Frictional force on the block is

1. proportional to the normal force on the block
2. proportional to the roughness of the surface and the block
3. None of these
4. zero

Q.

A flying machine offering the least frictional force should be?

Q.

In which of the following situations is frictional force acting?

1. A rock rolling down a mountain

2. An airplane flying in atmosphere

3. A person swimming in river

4. The Moon revolving around Earth

Q. When a body slides over the surface of another body, the resistance to its motion is called ___________ .

1. sliding friction
2. rolling friction
3. static friction
4. fluid friction

Q.

An inclined plane reduces the load needed to lift objects.

1. True
2. False

Q. Two blocks of same material are resting on a smooth surface, what will be the correct relations of friction force acting on them?


F1 and F2 represent the frictional force for blocks 1 and 2 respectively.

1. F1 > F2
2. F1 < F2
3. F1 = F2 = 2 N
4. F1 = F2 = 0 N

Q.

Give two examples in which friction is of advantage to us. Explain the advantage clearly.

Q.

State any two factors which directly affect the force of friction.

Q. If we apply a force towards left on a block kept at rest on the floor, then friction will act ___________.

1. upwards
2. towards right
3. downwards
4. towards left

Q. ntTh upper half of an inclined plane of inclination theta is perfectly smooth while the lower half is rough.A block starting from rest at the top of the plane will again come to rest at the bottom , if coefficient of friction between the block and the lower half of the plane is given by?n

Q. Imagine that an object is falling through a long straight glass tube held vertical; air has been removed completely from the tube. The object does not touch the walls of the tube. The frictional force on the object will be ____________.

​​

1. proportional to its surface area
2. proportional to its velocity
3. equal to zero
4. proportional to its mass.

Q. The upper half of an inclined plane of inclination \pm is perfectly smooth while lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom, if the coefficient of friction between the block and lower half of the plane is given by

Q. The static friction between two surfaces in contact is found to be 15 N, then the rolling friction between these two surfaces must be likely to be _____.

1. 25 N
2. 15 N
3. 20 N
4. 10 N

Q. A 5 kg block (A) ls placed on 10 kg block (B) which is at rest on the table: Coefficient of the friction between (A) and ( B)s 0.3 andbetween (B) and table is 04 A 40 N horizontal force is applied on the block (B), then the friction force between the block (A) and (B)(1)Zero(2)15 N(3)60 N4)40 N

Q. Two blocks of iron of different weights are kept on a cemented floor as shown in the figure. Which one of them would require a larger force to move it from the rest position?

1. Object A requires larger force.
2. Object B requires larger force.
3. Both object A and object B require same force which is not zero.
4. Both object A and object B require same force which is zero.

Q.

What do you understand by the term frictional force?

Q.

Which of the following is a self-adjusted force?

1. Rolling friction
2. Sliding friction
3. Static friction
4. Sliding and rolling friction

Q. An archer shot an arrow and after moving some distance, the arrow fell on the ground. Name the forces involved in the whole process.

1. Frictional force
2. Magnetic force
3. Muscular force
4. Gravitational force

Q. Explain why objects moving in fluids must have special shapes.

Q.

Which of the following forces is necessary to cause horizontal motion on the ground?

1. Normal force

2. Weight

3. Friction

4. We can walk without any force

Q. A block is at rest on a rough horizontal surface. There is no horizontal force on it. The weight of the block is 5 N. The frictional force on the block is _____.

1. proportional to the normal force on the block
2. proportional to the roughness of the surface and the block
3. zero
4. proportional to the area of contact of the block

Q. The drag offered by liquid will be maximum in:​

1. R
2. S
3. P
4. Q

Q. A block of weight 10 N is resting on a horizontal surface. If a person applies a force of 20 N as shown below, then the possible value of frictional force on the block due to surface will be __________.

1. 8 N
2. 0 N
3. 10 N
4. 12 N

Q. How does static friction adjust itsel

Q. You release two objects A and B from the same height (H) of an inclined plane. You see that object A goes larger distance than the object B before coming to rest. The objects have equal weights and their outer surfaces are equally polished. Which of the following options can be a possible case?

1. The size of the object A is larger than the size of the object B
2. The size of the object B is larger than the size of the object A
3. Object A is of spherical shape and object B is of rectangular box shape
4. Object B is of spherical shape and object A is of rectangular box shape

Q. A cube is pushed in such a way that it slides on a horizontal surface. How can the frictional force acting on the cube be increased?

1. By adding wheels to the cube
2. By applying lubricant between the cube and the surface
3. By polishing the outer surface of the cube
4. By placing another cube on top of it

Q. What is the maximum value upto which static friction can adjust itself ?