1000 questions & answers

What happens when air or water exerts frictional force on objects moving through them?

Why does an object in motion stop when no external force is applied on it?

Try to explain the importance of brake pads in the brake system of bicycles and automobiles.

Why do we sprinkle fine powder on the surface of a carrom board?

Can friction be entirely eliminated by using a large amount of lubricants? Why or why not?

This chapter discussed the force of friction and its effects on different surfaces. Can you illustrate with suitable examples how friction plays a crucial role in our day-to-day life? Discuss its advantages and disadvantages.

The force of friction varies depending on the type and nature of the surfaces in contact. Describe with examples how friction changes based on whether the surfaces are smooth, rough, or lubricated. How can one type of friction be converted into another to increase efficiency in machines or reduce wear and tear?

The chapter mentions static friction and sliding friction. Describe these two types of friction with examples. Why is sliding friction considered to be less than static friction?

The concept of wheels reducing friction was discussed in this chapter. Can you explain in detail why it is easier to roll an object than to slide it over another? How has the invention of the wheel revolutionised transportation and many other sectors?

Friction can also happen in fluid, like air and water, which is referred to as Fluid Friction or Drag. Explain how the shape and speed of an object moving through a fluid affect friction. Also, illustrate with real-life examples how friction in fluids is minimized, such as the design of aeroplanes or submarines.

Lubricants like oil, grease and graphite are used to reduce friction by forming a thin layer between the moving parts, preventing direct rubbing. Could you elaborate on how lubricants work, and why it may not be advisable to use oil as a lubricant on some machines?

Friction is known as a necessary evil. While it helps us in walking, holding things, writing, and so on, it also leads to wear and tear and energy loss due to the generation of heat. Discuss some practical examples where friction is a friend, and where it acts as an enemy.

Although we cannot eliminate friction completely, we can certainly reduce it. Discuss the various ways in which friction can be reduced as explained in this chapter. Are there any situations or examples where reducing friction might be harmful or undesirable?

Why do you think our national movement supported the idea that all adults have a right to vote?

Explain how sound is produced by a vibrating body.

What role does a medium play in the propagation of sound?

Can you explain the relationship between the amplitude of sound and its loudness?

What is frequency of a sound and how does it affect the pitch of the sound?

Which frequency range of sounds can humans hear?

What measures can be taken to limit noise pollution in a residential area?