Q1. Fill in the blanks.
Friction opposes the motion between
the surfaces in contact with each other.
Friction depends on the nature of
Friction produces heat.
Sprinkling of powder on the carrom board reduces
Sliding friction is less than the
The force of friction always opposes the
applied force. True
On rough surfaces, there are a lesser number
of irregularities. False
Sliding friction is slightly smaller than
the static friction. True
Friction is caused by the irregularities on
the two surfaces in contact. True
Soles of shoes wear out due to gravity. False
Q3. Which force helps things to move and stop?
Ans. Frictional force
Q4. What enables a ladder to lean against the wall?
Q5. Name two common lubricants.
Ans. Oil and Grease
Q6. Mention one simple method of reducing friction between two
Q7. What is drag?
The frictional force exerted by fluids is also called drag.
Q8. Which type of surface produces less friction?
Ans. Smooth surface produces less friction.
Q9. Why the soles of our shoes wear out gradually?
Ans. The soles of shoes wear out gradually due to
Q10. Which type of surface produces more friction?
Rough surface produces more friction.
Q11. Why ball bearings are used in machines?
What is the purpose of using ball bearing in machine?
Ans. Ball bearings reduce friction. Thus, they are
used in machines.
Q12. Write any two machines in which ball bearings are used.
Ans. Ceiling fans and Bicycles
Q13. What makes the steps of foot over-bridges at Railway
Stations to wear out slowly?
Ans. Frictional force
Q14. What are lubricants?
The substances which reduce friction are called lubricants.
Q15. Why do we sprinkle fine powder on the carrom board?
Ans. Powder is sprinkled on the carrom board to reduce
Q16. Name the force responsible for wearing out of car tyres.
Ans. Frictional force is responsible the wearing of
Q17. What is the direction of force of friction acting on a
What is the direction of force of friction?
Ans. The force of friction always opposes the applied
Q18. Which force always opposes motion?
What is the force that always opposes motion?
Ans. Friction force always opposes motion.
Q19. What is done to increase friction between the tyres and
Ans. The tyres of the vehicle are treaded to increase
Q20. When does static friction come into play?
Ans. Static friction comes into play when we try to
move an object at rest.
Q21. When does sliding friction come into play?
Ans. Sliding friction comes into play when an object
is sliding over another.
Q22. Why is the surface of a slide polished to make it smooth?
Ans. The surface of a slide polished to make it smooth
in order to reduce friction.
Q23. Why do kabaddi players rub their hands with dry soil?
Ans. Kabaddi players rub their hands with soil for a
better grip of their opponents.