Factors Affecting Friction

Q.

What causes friction?

Q.

What are some of the most common examples of helpful friction?

Q. Frictional force between two objects depends on the weight of the object which has been kept above the other object.

1. False
2. True

Q.

State the energy changes in the following while in use:

A steam engine.

Q.

Frictional force acts between two bodies even when they are not in contact.

1. True

2. False

Q. The speed of an object falling through air is same as the speed of an object falling in a liquid medium.

1. False
2. True

Q.

A piece of paper takes much longer to fall than a stone through the same distance. Explain the reason.

Q.

Two identical rectangular strips, one of copper and the other of steel, are riveted to form a bi-metal strip. On heating, the bi-metal strip will

1. Bend

2. Twist

3. Elongate

4. Shorten

Q. Does friction depends upon the area of contact . If it depends then explain how? If not then why?

Q.

Neha has to push a light weight box and Sohit has to push a heavier box on the same floor. Which of the following is true?

1. It runs out of push

2. It rubs against the ice

3. It runs out of electricity

4. Force of gravity made it slow

Q.

Name the energy transformation takes in the following instruments.
I. Steam engine

Q.

A bucket of soapy water has been accidentally spilled on a marble floor. Which of the following statements is correct?

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

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

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

4. It will be easier to walk after the spilling

Q.

People slip when they step on a banana peel. Which of these is a possible reason?

1. Banana peel provides less friction

2. Banana peel provides more friction

3. None of these

4. Banana peel provides no friction

Q. On which of the following factors, friction between two objects/surfaces does not depend?

1. temperature
2. surface roughness
3. intemolecular interactions
4. mass of objects

Q. A stationary block remains stationary even after applying a horizontal force. This means that frictional force is applied force.

1. equal to
2. greater than
3. less than

Q. Which of the following factors does not affect the friction in a fluid?

1. Object speed
2. Object shape
3. Fluid nature
4. Fluid colour

Q. Applying oil to machines increases their efficiency.

1. Towards left

2. Towards right

Q.

Which of the following method increases friction ?

1. Grooving

2. Streamlining

3. Lubricating

4. Using rollers

Q. Choose the correct pair for the given elements and their presence in our body.

1. Iron
2. Blood
3. Muscles
4. Calcium
5. Carbon
6. Bones
7. Lungs
8. Oxygen

Q. Four objects, of different weights, are coming down a slide of metal sheet. Which of them would experience the greatest amount of frictional force on them?

1. object A = 25 kg
2. object B = 50 kg
3. object C = 75 kg
4. object D = 125 kg

Q. Pins are fixed with the help of wax as shown in the following cases. In which order will the pins fall?​

1. R > Q > P​
2. P > Q > R​
3. P > R > Q​
4. Q > P > R​

Q.

Two blocks of iron of different masses are kept on a cemented floor as shown in Fig.12.2. Which one of them would require a larger force to move it from the rest position?

Fig. 12.2

Q.

Fluid friction is ___ offered by a fluid against the relative motion of its layers.

Q. In which of the following situations is frictional force acting?

1. An airplane flying in atmosphere
2. A rock rolling down a mountain
3. The Moon revolving around Earth
4. A person swimming in river

Q.

The friction will change if the above object is dragged along the top surface instead of the bottom.

1. True

2. False

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. Which of the following help reduce friction between two surfaces?

1. Ball bearings
2. Grease
3. Powder
4. Oil
5. Spikes
6. Wheels
7. Polishing
8. Sand

Q. Identify the cause of friction.

1. Interlocking
2. All of the above
3. Adhesion
4. Plowing effect

Q.

When we put cup upside down in a bucket filled with water, and when we take it out it is little bit difficult. Why?

Q. In which of the following situations is frictional force acting?

1. A person swimming in river
2. The Moon revolving around Earth
3. An airplane flying in atmosphere
4. A rock rolling down a mountain