Polishing Surfaces in Contact to Change Friction

Q.

Friction is a necessary evil. Comment.

Q.

What is meant by lubrication ? Why is it important ?

Q.

Why do we sprinkle fine powder on carrom board?

Q. Why are double tyres provided at the rear wheels of a truck.

Q.

The wheels of automobiles are made circular. Why?

Q.

Why does a man slip when he steps on a banana peel thrown on the road?

Q.

How will you reduce friction between those machine parts which rub against each other ? Give the simplest method.

Q.

Why are lubricants (oil or grease) applied to rubbing surfaces of machines?

Q.

Name the substance used to reduce friction between the moving parts of a machine.

Q.

Explain with the help of diagrams, how the use of oil reduces friction between two surfaces in contact with each other.

Q.

Why does oiling the axles of a bicycle make the bicycle move more easily?

Q. Mention three methods of reducing friction in a machine

Q.

A)Explain why it is convient to pull the luggages fitted with rollers?

Q.

The proper use of lubricants cannot reduce

1. Inertia

2. Static friction

3. Sliding friction

4. Rolling friction

Q.

Why are wheels circular?

Q. friction is a nonconsertive force and electomagnetic force are conservative forces.but friction is also a electromagnetic force. then how is it non conservative force?

Q.

Increased smoothness increases friction

Q. Is friction acting on a surface can be zero?

Q.

It is easier to roll a barrel than to pull it along the road. Why?

Q.

Why is the surface of a slide polished to make it smooth?

Q.

Why are ball bearings used in machines?

1. Sliding friction replaces rolling friction.

2. Static friction replaces rolling friction.

3. Rolling friction replaces sliding friction.

4. Rolling friction replaces static friction.

Q.

Kabaddi players rub their hands with soil for a better grip of their opponents as this would decrease friction

1. False

2. True

Q.

In order to reduce friction in machines, ball bearing are used in between the moving parts.

1. True
2. False

Q.

Which force gets reduced when the two surfaces in contact are polished to make them smooth?

Q.

Which of the following is not used to reduce friction?

1. Using oil between contact surfaces

2. Using grease between contact surfaces

3. Using ball-bearing

4. Making scratches on the contact surfaces

Q.

How do ball bearings help reducing friction ?

Q. Which of the following should be used to reduce friction on a carrom board?
(a) a lubricating oil
(b) a dry lubricant
(c) a layer of grease
(d) a ball bearing

Q. How would the absence of friction change the world around us?

Q.

How can you minimise the rolling friction?

Q.

List two ways in which friction can be increased and two ways in which it can be decreased to our advantage.