Nature of surface in contact

Q. Why does friction occur

Q.

Applying oil to machines increases the efficiency of the machine.

1. Towards right

2. Towards left

Q.

Why is it difficult to walk on marshy ground? Explain

Q.

Friction can be reduced by using

1. lubricants

2. streamlined shape

3. ball bearings

4. all of them

Q. Which factor is responsible for friction between two smooth and even surfaces?

1. Adhesion
2. Roughness
3. Uneven interlocking of surfaces
4. Smoothness

Q.

Suppose you accidently spill soapy water on a marble floor. Which of the following statements is correct?

1. It will be easier to walk after the spilling

2. It will be easier to walk after the spilling because force of friction increase

3. It will be difficult to walk after the spilling because force of friction increases

4. It will be difficult to walk after the spilling because force of friction decreases.

Q. A force F is applied towards right on a block sliding at a speed of 2 m/s on a horizontal surface as shown below. Choose the correct statement regarding friction acting on the block at this instant.

1. irregularities on the surface
2. attraction between objects
3. repulsion between objects
4. volume of the two objects

Q.

A Kabaddi player is trying to increase his grip. He attempts to rub his hands with one of the following materials. Which one should he choose for a better grip?

1. Oil

2. Grease

3. Water

4. Coarse material

Q.

Assuming that a toy car is pushed with the same force, on which of the following surfaces would it travel the farthest?

1. A carpet

2. A floor on which sand is sprinkled

3. A wet marble floor

4. A garden

Q.

Friction can be reduced to zero by applying lots of lubricants between surfaces.

1. rubbing of hands gainst each other

2. rubbing of eraser against paper

Q.

Four identical wooden blocks are slid with same initial velocities on four different horizontal surfaces - sand, concrete, clay and ice. On which of these surfaces, will the distance travelled be maximum?

1. Ice

2. Sand

3. Concrete

4. Clay

Q. Which of the following methods can be used to increase friction between two surfaces?

1. Applying lubricant between surfaces

2. Using powder between surfaces

3. Making the surfaces more irregular
4. Using ball bearings

Q. A ball rolling on ground slows down primarily because of:

1. Any rough surface
2. Any smooth surface
3. Half smooth half rough
4. Wedge shaped smooth

Q. Which of the following statements is correct regarding friction between two surfaces in contact?

1. Friction exists between surfaces only if they are rough
2. Smooth surfaces do not have friction
3. Friction is solely because of the interlocking of uneven surfaces
4. All the statements are incorrect

Q. Which of the following factors are responsible for friction?

1. Adhesion or stickiness
2. Plowing effect
3. Surface roughness
4. Density of the object

Q. Which factor is responsible for friction between two smooth and even surfaces?

1. Roughness
2. Adhesion
3. Smoothness
4. Uneven interlocking of surfaces

Q.

Assuming all surfaces to be equally smooth, friction will change if the object is flipped and then dragged, as shown in the figure.

1. True

2. False

Q.

Arrange the following in increasing order of surface roughness:

• Sandpaper
• Polished steel
• Cardboard

1. Sandpaper < Cardboard < Polished steel
2. Polished steel < Sandpaper < Cardboard
3. Polished steel < Cardboard < Sandpaper
4. Cardboard < Sandpaper < Polished steel

Q. Applying lubricants to machines increases their efficiency.

1. Towards left

2. Towards right

Q. Why is talcum powder sprinkled on carrom board?

1. Make the board durable
2. To reduce friction
3. Maintain friction
4. To increase friction