Advertisements
Advertisements
प्रश्न
Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain.
Advertisements
उत्तर
When we take off our sweaters in winter, we hear a crackling sound. This is because removing our sweater acquires charge due to friction between the sweater and our body. As a result, we hear a crackling sound from the sweater.
APPEARS IN
संबंधित प्रश्न
Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.
When a glass rod is rubbed with a piece of silk cloth the rod ______.
Give an example to illustrate the existence of the force of friction.
List three ways of reducing friction.
Arrange the following in descending order:
- static friction
- sliding friction and
- rolling friction?
Answer the following.
What do you understand by a force?
Answer the following in a word or two or in a sentence.
Why does a rolling ball stop after moving some distance?
Answer the following in detail.
What are the various effects of force? State one example of each.
Fill in the blank.
Rolling friction offers ............. resistance than sliding friction.
Fill in the blank.
Sliding friction and rolling friction are types of .................. friction.
Tick the most appropriate answer
Friction always
Tick the most appropriate answer.
Friction is offered by
Answer the following in short.
When you push something heavy, the resistance you feel decreases as soon as the object starts moving. Explain the reason.
Answer the following in short.
List the various states of matter that offer frictional force?
Match the following.
| Column I | Column II | |
| a) | Static friction | Viscosity |
| b) | Kinetic friction | Least friction |
| c) | Rolling friction | Objects are in motion |
| d) | Friction between the liquid layers | Objects are sliding |
| e) | Sliding friction | Objects are at rest |
Explain how friction can be minimized.
Assertion: Friction always opposes the motion.
Reason: Whenever one surface moves or tries to move over another surface, the force of friction starts acting on the surfaces.
Assertion: There is a danger of a vehicle skidding on a wet road.
Reason: The tires of the vehicle lose their grip on the road due to an increase in friction due to the presence of water on the road.
Complete the analogy.
Knot in a thread : ______ friction :: Ball bearing : ______ friction.
