CBSE Class 8 Science Chapter 9 Friction Very Short Answer Questions
Question 1. Will the force of friction come into play when a raindrop rolls down a glass window pane?
Answer: Yes, friction comes into play when two surfaces are in contact, but in a very small amount.
Question 2. If a body is moving on a rough horizontal surface towards the east, then in which direction will the frictional force act?
Answer: Frictional force always acts in the direction opposite to the direction of motion, so it will act towards the west.
Read And Learn More CBSE Class 8 Science Very Short Questions And Answers
Question 3. The figure shows two boys applying force to a box. If the magnitude of the force applied by each is equal, will the box experience any force of friction?
Answer: No, the force applied by both boys is equal. So, the net force will be zero, and hence friction force will not come into play.
Question 4. It is easier to drag a carpet from the floor, but it is difficult to drag the carpet when someone is sitting on it. Explain the reason behind it.
Answer: If the two surfaces are pressed harder, then the force of friction will increase. So, it is easy to drag a carpet when nobody is sitting on it, but when a person is sitting on it, then it produces more friction.
Question 5. Why does a matchstick catch fire when it is rubbed on a rough surface?
Answer: On rubbing the matchstick on a rough surface, the temperature increases due to friction, making the matchstick catch fire.
Question 6. The jar of a mixer becomes hot when it is run for a few minutes. Comment.
Answer: Due to friction, the jar of a mixer becomes hot when it is run for a few minutes.
Question 7. Give n reason for railing friction as n necessary evil.
Answer: Friction is a necessary evil because it causes a lot of wear and tear.
Question 8. Why do kabaddi players rub their hands with soil?
Answer: Kabaddi players rub their hands with soil to increase the friction, so that they can grip the opposing team players firmly.
Question 9. Why do weightlifters apply chalk powder on their palms while lifting weights?
Answer: It increases the roughness in their hand. This provides a better grip while lifting weights.
Question 10. Why are oil, creams, and grease called lubricants?
Answer: Oil, creams and grease, when applied on a surface, make it smooth, thus reducing friction, so these are called lubricants.
Question 11. Can we eliminate friction?
Answer: No, we cannot eliminate friction because it is a characteristic property (molecular property) of a material.
Question 12. What is the special shape of the objects moving in fluids?
Answer: Streamlined shape is the special shape given to objects moving in fluids.
Question 13. Explain fluid friction brief.
Answer: When an object moves in a fluid, the resistance to the movement of the object exerted by the fluid is called fluid friction.
Question 14. Why does an arrow with a pointed tip move faster in the air than one with a flat tip?
Answer: The arrow with a pointed tip suffers small air resistance due to its pointed shape, so it moves faster.